MERCURY AND AIR TOXIC ELEMENT 

IMPACTS OF COAL COMBUSTION 

BY-PRODUCT DISPOSAL AND UTILIZATION

Final Report 

(for the period January 23, 2003 – December 31, 2006) 

AAD Document Control 

U.S. Department of Energy 

National Energy Technology Laboratory 

PO Box 10940, MS 921-143 

Pittsburgh, PA 15236-0940 

Cooperative Agreement No. DE-FC26-02NT41727 

Performance Monitor: Lynn Brickett 

Prepared by: 

David J. Hassett 

Loreal V. Heebink 

Debra F. Pflughoeft-Hassett 

Tera D. Buckley 

Erick J. Zacher 

Energy & Environmental Research Center 

University of North Dakota 

15 North 23rd Street, Stop 9018 

Grand Forks, ND 58202-9018 

Mei Xin 

Mae Sexauer Gustin 

Department of Natural Resources and Environmental Sciences 

University of Nevada, Reno 

1664 North Virginia Street 

FA 128, Mail Stop 370 

Reno, NV 89557 

Rob Jung 

5192 8th Avenue North 

Grand Forks, ND 58203 

2007-EERC-10-03 October 2007 
DOE DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 

This report is available to the public from the National Technical Information Service, U.S. 

Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders 

accepted at (703) 487-4650. 

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental 

Research Center (EERC), an agency of the University of North Dakota, as an account of work 

sponsored by the U.S. Department of Energy (DOE), the Electric Power Research Institute 

(EPRI), and Reliant Energy. Because of the research nature of the work performed, neither the 

EERC nor any of its employees makes any warranty, express or implied, or assumes any legal 

liability or responsibility for the accuracy, completeness, or usefulness of any information, 

apparatus, product, or process disclosed or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial product, process, or service by trade 

name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its 

endorsement or recommendation by the EERC. 

ACKNOWLEDGMENTS 

The authors wish to gratefully acknowledge the guidance, support, and assistance of the 

DOE National Energy Technology Laboratory Performance Monitor, Lynn Brickett, and the 

industrial sponsor representatives: 

Center for Air Toxic Metals® – John Pavlish 

Cinergy – Darlene Radcliffe and R. James Meiers 

EPRI – Ken Ladwig 

Great River Energy – Mark Strohfus and Diane Stockdill 

North Dakota Lignite Research Council – Harvey Ness and Jeff Burgess 

U.S. Waste Activities Group – James Roewer 
The authors also wish to acknowledge EERC colleague Research Microbiologist John 

Gallagher (1955–2004), who was instrumental in preparing the project proposal and in initiating 

the microbiological work described in this report. The project team is honored to have worked 

with him and to have counted him as a colleague and friend. 

The guidance and assistance of several other EERC colleagues is also gratefully 

acknowledged, including Kurt Eylands, Bruce Dockter, Dennis Laudal, Lucinda Hamre, Mike 

Holmes, Stan Miller, Carolyn Nyberg, Jeff Thompson, and Chad Wocken. 

The authors also wish to thank EERC support staff, including Kari Lindemann, Tami 

Votava, Tobe Larson, Michelle Olderbak, and Shannan Longsdorf for all the assistance in 

performing and completing this project. 
MERCURY AND AIR TOXIC ELEMENT IMPACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION

ABSTRACT 

 The University of North Dakota Energy & Environmental Research Center (EERC) 

conducted a multiyear study to evaluate the impact of mercury and other air toxic elements 

(ATEs) on the management of coal combustion by-products (CCBs). The ATEs evaluated in this 

project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included 

laboratory tasks to develop measurement techniques for mercury and ATE releases, sample 

characterization, and release experiments. A field task was also performed to measure mercury 

releases at a field site. 

 Samples of fly ash and flue gas desulfurization (FGD) materials were collected 

preferentially from full-scale coal-fired power plants operating both without and with mercury 

control technologies in place. In some cases, samples from pilot- and bench-scale emission 

control tests were included in the laboratory studies. Several sets of “paired” baseline and test fly 

ash and FGD materials collected during full-scale mercury emission control tests were also 

included in laboratory evaluations. Samples from mercury emission control tests all contained 

activated carbon (AC) and some also incorporated a sorbent-enhancing agent (EA). 

 Laboratory release experiments focused on measuring releases of mercury under 

conditions designed to simulate CCB exposure to water, ambient-temperature air, elevated 

temperatures, and microbes in both wet and dry conditions. 

 Results of laboratory evaluations indicated that: 

• Mercury and sometimes selenium are collected with AC used for mercury emission 

control and, therefore, present at higher concentrations than samples collected without 

mercury emission controls present. 

• Mercury is stable on CCBs collected from systems both without and with mercury 

emission controls present under most conditions tested, with the exception of vaporphase releases of mercury exposed to elevated temperatures. 

• The presence of carbon either from added AC or from unburned coal can result in 

mercury being sorbed onto the CCB when exposed to ambient-temperature air. 

 The environmental performance of the mercury captured on AC used as a sorbent for 

mercury emission control technologies indicated that current CCB management options will 

continue to be sufficiently protective of the environment, with the potential exception of 

exposure to elevated temperatures. The environmental performance of the other ATEs 

investigated indicated that current management options will be appropriate to the CCBs 

produced using AC in mercury emission controls. 
i 

TABLE OF CONTENTS 

LIST OF FIGURES ....................................................................................................................... iv 

LIST OF TABLES......................................................................................................................... vi 

NOMENCLATURE ....................................................................................................................... x 

EXECUTIVE SUMMARY .......................................................................................................... xii 

1.0 INTRODUCTION................................................................................................................. 1 

2.0 BACKGROUND................................................................................................................... 3 

3.0 OBJECTIVES ....................................................................................................................... 5 

4.0 EXPERIMENTAL ................................................................................................................ 6 

4.1 Literature Search.......................................................................................................... 6 

4.2 Analytical Methods Selection...................................................................................... 6 

4.3 Sample Identification and Selection ............................................................................ 6 

 4.3.1 Sample Prioritization ....................................................................................... 7 

 4.3.2 Sampling and Storage Procedures ................................................................... 8 

 4.3.3 Sample Collection.......................................................................................... 10 

4.4 Chemical and Physical Characterization ................................................................... 10 

 4.4.1 Analytical Methods for Characterization and Release Experiments ............. 11 

4.5 Laboratory Evaluation of ATE Releases ................................................................... 12 

 4.5.1 Direct Leaching ............................................................................................. 13 

 4.5.2 Vapor-Phase Mercury Transport ................................................................... 15 

 4.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport ............. 20 

4.6 Field Investigations.................................................................................................... 25 

 4.6.1 Field Task 1 ................................................................................................... 25 

 4.6.2 Alternate Field Task ...................................................................................... 26 

4.7 Data Reduction and Interpretation............................................................................. 27 

5.0 RESULTS AND DISCUSSION ......................................................................................... 28 

5.1 Literature Search........................................................................................................ 28

5.2 Analytical Methods Selection.................................................................................... 29 

5.3 Sample Identification and Selection .......................................................................... 30 

 5.3.1 Sample Prioritization ..................................................................................... 31 

 5.3.2 Sample Handling ........................................................................................... 33 

 5.3.3 Sample Descriptions...................................................................................... 34 

Continued . . . 
ii 

TABLE OF CONTENTS (continued) 

5.4 Chemical and Physical Characterization ................................................................... 36 

 5.4.1 Total Mercury and ATEs............................................................................... 36 

 5.4.2 Total Bulk Chemical Composition................................................................ 40 

 5.4.3 LOI and Moisture Content............................................................................. 41 

 5.4.4 Carbon Forms ................................................................................................ 47 

5.5 Laboratory Evaluation of ATE Releases ................................................................... 48

 5.5.1 Direct Leaching ............................................................................................. 48 

 5.5.2 Vapor-Phase Transport.................................................................................. 62 

 5.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport ............. 75

5.6 Field Investigations.................................................................................................... 80 

 5.6.1 Field Task 1 ................................................................................................... 81 

 5.6.2 Alternate Field Task ...................................................................................... 87

 5.7 Data Reduction and Interpretation............................................................................. 89 

6.0 CONCLUSIONS AND RECOMMENDATIONS.............................................................. 90 

7.0 REFERENCES.................................................................................................................... 93 

SAMPLE IDENTIFICATION FORM ..........................................................................Appendix A 

DRAFT STANDARD METHOD FOR SYNTHETIC GROUNDWATER 

LEACHING PROCEDURE ..........................................................................................Appendix B 

MERCURY INFORMATION CLEARINGHOUSE REPORTS..................................Appendix C 

LABORATORY METHODS FOR THE EVALUATION OF POTENTIAL 

RELEASE OF MERCURY FROM COAL UTILIZATION BY-PRODUCTS............Appendix D 

SAMPLE PRIORITIZATION....................................................................................... Appendix E 

SAMPLE IDENTIFICATION NUMBER AND DESCRIPTIONS.............................. Appendix F 

TOTAL TRACE ELEMENTAL DATA .......................................................................Appendix G 

FGD LIQUOR TOTAL TRACE ELEMENTAL CONCENTRATION AND 

pH DATA.......................................................................................................................Appendix H 

TOTAL BULK CHEMICAL COMPOSITION DATA ................................................. Appendix I 

MOISTURE CONTENT AND LOI DATA...................................................................Appendix J 

Continued . . . 
iii 

TABLE OF CONTENTS (continued) 

pH DATA.......................................................................................................................Appendix K 

CARBON FORMS DATA ............................................................................................ Appendix L 

LEACHATE DATA .....................................................................................................Appendix M 

MERCURY AND AIR TOXIC ELEMENT LEACHING FROM COAL 

COMBUSTION BY-PRODUCTS ................................................................................Appendix N 

SUMMARY OF LONG-TERM AMBIENT-TEMPERATURE RELEASE 

DATA ............................................................................................................................Appendix O 

ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT 

FROM COAL COMBUSTION BY-PRODUCTS ........................................................ Appendix P 

ELEVATED-TEMPERATURE MERCURY RELEASE DATA.................................Appendix Q 

MICROBIOLOGICALLY MEDIATED MERCURY AND AIR TOXIC ELEMENT 

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS ..............................Appendix R 

MICROBIOLOGICALLY MEDIATED LEACHING AND VAPOR-PHASE 

TRANSPORT TASK SAMPLE SET............................................................................ Appendix S 

FIELD INVESTIGATIONS TASK SAMPLE SET AND FUNDAMENTAL 

CHARACTERIZATION DATA................................................................................... Appendix T 

ALTERNATE FIELD TASK DATA ............................................................................Appendix U 
iv 

LIST OF FIGURES 

2-1 EPA information on mercury emissions ............................................................................... 4 

4-1 Categorization of trace elements associated with coal ash based on volatility..................... 7 

4-2 Mercury distribution in a power plant................................................................................... 9 

4-3 Example LTL results for boron........................................................................................... 14 

4-4 Indirect evidence of ettringite formation using SGLP and LTL ......................................... 15 

4-5 Ambient-temperature mercury vapor release collection apparatus..................................... 17 

4-6 Mercury thermal desorption apparatus................................................................................ 18 

4-7 Typical thermal desorption curve for fly ash ...................................................................... 19 

4-8 Example of thermal desorption curve for an FGD material................................................ 19 

4-9 Early microbiologically mediated mercury vapor-phase collection apparatus 

 utilizing a wrist action shaker to facilitate mixing .............................................................. 21 

4-10 Microbiologically mediated mercury vapor-phase collection apparatus 

 utilizing a stir plate to facilitate mixing .............................................................................. 22 

4-11 Field sampling site map....................................................................................................... 27 

4-12 CCB–soil mercury vapor release collection apparatus ....................................................... 28 

5-1 Fly ash 18-hour SGLP leachate mercury plotted against total mercury content................. 52 

5-2 Fly ash + AC and/or EA 18-hour SGLP leachate mercury plotted against total 

 mercury content................................................................................................................... 52 

5-3 Arsenic 18-hour SGLP and 30- and 60-day LTL leaching data for a paired sample set .... 56 

5-4 Sample Set 1 (194-day) long-term ambient-temperature mercury release or 

 sorption as related to blank values ...................................................................................... 66 

5-5 Sample Set 2 (188-day) long-term ambient-temperature mercury release or 

 sorption as related to blank values ...................................................................................... 66 

Continued . . . 
v 

LIST OF FIGURES (continued) 

5-6 Sample Set 3 (187-day) long-term ambient-temperature mercury release or 

 sorption as related to blank values ...................................................................................... 67 

5-7 Long-term ambient-temperature mercury release rate from 

 Samples 04-082 and 04-083................................................................................................ 70 

5-8 Typical two-peak mercury desorption curve for fly ash ..................................................... 74 
vi 

LIST OF TABLES 

4-1 Microbiological Rerelease Apparatus Modifications.......................................................... 22 

4-2 Microbiological Experimental Incubation Conditions........................................................ 24 

4-3 Mercury Measurement Site Descriptions............................................................................ 26 

5-1 Summary of Fly Ash Samples and Fundamental Characterization Data ............................ 32 

5-2 Summary of FGD–SDA Samples and Fundamental Characterization Data....................... 33 

5-3 Summary of Eastern Bituminous Wet FGD Material Samples and Fundamental 

 Characterization Data.......................................................................................................... 33 

5-4 Paired Samples and Fundamental Characterization Data.................................................... 34 

5-5 Range of Total Trace Elements in Fly Ash Samples .......................................................... 36 

5-6 Range of Total Trace Elements in FGD–SDA Samples ..................................................... 37 

5-7 Range of Total Trace Elements in Wet FGD Material Samples ......................................... 37 

5-8 Total Trace Elements in FGD Gypsum Samples Comparing SCR On and SCR Off......... 38 

5-9 Range of Total Trace Elements in FGD Liquor Samples ................................................... 39 

5-10 Paired Samples and Total ATE Content ............................................................................. 40 

5-11 Summary of Total Bulk Chemical Composition Compared to ASTM C618 

 Specifications ...................................................................................................................... 41 

5-12 Range of Moisture Content and LOI in Fly Ash Samples .................................................. 41 

5-13 Range of Moisture Content and LOI in FGD–SDA Samples ............................................. 42 

5-14 Range of Moisture Content and LOI in FGD Material Solid Samples ............................... 42 

5-15 Paired Samples Moisture Content and LOI......................................................................... 43 

5-16 Range of pH in Fly Ash Samples ........................................................................................ 44 

Continued . . . 
vii 

LIST OF TABLES (continued) 

5-17 Fly Ash Samples Exhibiting a Greater Than One pH Unit Change over a 

 24-hour Period..................................................................................................................... 45 

5-18 Range of pH in FGD–SDA Samples................................................................................... 46 

5-19 Ranges of pH in Wet FGD Material Sample....................................................................... 47 

5-20 Ranges of pH in Liquid from Wet FGD Material Samples................................................. 47 

5-21 Number of Samples per Carbon Form with Total Hg and LOI Ranges.............................. 48 

5-22 Ranges of Leachate Results for Fly Ash ............................................................................. 49 

5-23 Ranges Leachate Results for FGD–SDA ............................................................................ 49 

5-24 Ranges of Leachate Results for Wet FGD Material............................................................ 49 

5-25 Ranges of Fly Ash Mercury Leachate Results by Leaching Test ....................................... 50 

5-26 Ranges of Fly Ash Mercury Leachate and Leachate pH Results by Coal Type 

 and Leaching Test ............................................................................................................... 51 

5-27 Paired Samples Mercury 18-hour SGLP and TCLP Leachates and Fundamental 

 Characterization Data.......................................................................................................... 53 

5-28 Paired Mercury Leachates and Fundamental Characterization Data of Fly 

 Ash Samples with Enhancing Agent and ACI .................................................................... 53 

5-29 Paired Mercury Leachates and Fundamental Characterization Data of Fly 

 Ash Samples with AC ......................................................................................................... 54

5-30 Ranges of FGD–SDA Mercury Leachate Results by Leaching Test .................................. 54 

5-31 Paired FGD–SDA mercury leachates and fundamental characterization data.................... 54 

5-32 Ranges of Wet FGD Material Mercury Leachate Results by Leaching Test...................... 55 

5-33 Range of Fly Ash Arsenic Leachate Results by Leaching Test .......................................... 55 

5-34 Ranges of FGD–SDA Arsenic Leachate Results by Leaching Test ................................... 55 

Continued . . . 
viii 

LIST OF TABLES (continued) 

5-35 Ranges of Wet FGD Material Arsenic Leachate Results by Leaching Test ....................... 56 

5-36 Ranges of Fly Ash Cadmium Leachate Results by Leaching Test ..................................... 57 

5-37 Ranges of Fly Ash + FGD–SDA Material Cadmium Leachate Results by 

 Leaching Test ...................................................................................................................... 58 

5-38 Ranges of Wet FGD Material Cadmium Leachate Results by Leaching Test.................... 58 

5-39 Ranges of Fly Ash Chromium Leachate Results by Leaching Test.................................... 59 

5-40 Ranges of FGD–SDA Chromium Leachate Results by Leaching Test............................... 59 

5-41 Ranges of Wet FGD Material Chromium Leachate Results by Leaching Test .................. 59 

5-42 Ranges of Fly Ash Lead Leachate Results by Leaching Test ............................................. 60 

5-43 Ranges of FGD–SDA Material Lead Leachate Results by Leaching Test ......................... 60 

5-44 Ranges of Wet FGD Material Lead Leachate Results by Leaching Test............................ 60 

5-45 Ranges of Fly Ash Nickel Leachate Results by Leaching Test .......................................... 61 

5-46 Ranges of FGD-SDA Nickel Leachate Results by Leaching Test...................................... 61 

5-47 Ranges of Wet FGD Material Nickel Leachate Results by Leaching Test......................... 61 

5-48 Ranges of Fly Ash Selenium Leachate Results by Leaching Test...................................... 62 

5-49 Ranges of FGD–SDA Selenium Leachate Results by Leaching Test................................. 62 

5-50 Ranges of Wet FGD Material Selenium Leachate Results by Leaching Test..................... 62 

5-51 Long-Term Ambient-Temperature Sample Set 1 Summary .............................................. 64 

5-52 Long-Term Ambient-Temperature Sample Set 2 Summary .............................................. 65 

5-53 Long-Term Ambient-Temperature Sample Set 3 Summary ............................................... 68 

5-54 Long-Term Ambient-Temperature Sample Set 4 Summary .............................................. 69 

Continued . . . 
ix 

LIST OF TABLES (continued) 

5-55 Summary of Fly Ash Samples Evaluated in Elevated-Temperature Mercury 

 Release Experiments ........................................................................................................... 72 

5-56 Summary of FGD–SDA and Wet FGD Material Samples Evaluated in 

 Elevated-Temperature Mercury Release Experiments........................................................ 73 

5-57 Range of Fly Ash Peak Mercury Release Temperatures at Elevated Temperature ............ 74 

5-58 Range of FGD–SDA and Wet FGD Material Peak Mercury Release Temperatures at 

 Elevated Temperature ......................................................................................................... 74 

5-59 Microbiological Release Experiment Sample Summary, Experiment 7............................. 76 

5-60 Microbiological Experiment 7 Eh and pH Results.............................................................. 77 

5-61 Vapor-Phase Mercury Release Results, Experiment 7........................................................ 77 

5-62 Microbiological Leached Total Trace Element Results, Experiment 7 .............................. 78 

5-63 Summary of Vapor-Phase Mercury Releases from Microbiologically Mediated 

 Experiments on Fly Ash Samples ....................................................................................... 78 

5-64 Summary of Vapor-Phase Mercury Releases from Microbiologically Mediated 

 Experiments on FGD–SDA and Wet FGD Filtercake Samples.......................................... 79 

5-65 Field Sample Composites and Associated CCB Mercury Analysis Results, Average ....... 82 

5-66 Range of Fundamental Characterization Data in Field Samples Collected by EERC ........ 82 

5-67 Summary of Mercury Fluxes Measured from Landfill Facilities........................................ 83 

5-68 Summary of Scaling of Emissions Using Field Site Data................................................... 84 

5-69 Comparison of Scaling of Hg Flux Using In Situ Data from Three Landfill Sites............. 85 

5-70 Average CCB Landfill Mercury Readings and Standard Deviation ................................... 87 

5-71 Alternative Field Task (CCB–soil) Elemental Mercury Results Summary ........................ 88 

5-72 Alternative field task (CCB–soil) Organomercury Results Summary ................................ 89 

5-73 Overall Elemental Mercury Vapor Profiles in Noted Tasks ............................................... 91 
x 

NOMENCLATURE 

AA atomic absorption 

AAS atomic absorption spectrophotometer 

AC activated carbon 

ACI activated carbon injection 

AF atomic fluorescence 

ASTM American Society for Testing and Materials 

ATE air toxic element 

CAA Clean Air Act 

CARRC® Coal Ash Resources Research Consortium® 

CCB coal combustion by-product 

CVAAS cold-vapor atomic absorption spectrometry 

CVAFS cold-vapor atomic fluorescence spectrometry 

DMA direct mercury analyzer 

DOE U.S. Department of Energy 

EA enhancing agent 

EERC Energy & Environmental Research Center 

EPA U.S. Environmental Protection Agency 

ESP electrostatic precipitator 

FGD flue gas desulfurization 

GC gas chromatography 

HDPE high-density polyethylene 

HNO3 nitric acid 

ICP–AES inductively coupled plasma–atomic emission spectroscopy 

ICP–MS inductively coupled plasma–mass spectroscopy 

KCl potassium chloride 

LLQ lower level of quantitation 

LOI loss-on-ignition 

LTL long-term leaching 

MPN most probable number 

MWLP mine water leaching procedure 

NA not applicable 

NETL National Energy Technology Laboratory 

NMLRC National Mine Land Reclamation Center 

NOx nitrogen oxides 

NQ not quantitated 

NT not tested 

ORD Office of Research and Development 

pc pulverized coal 

PCD pollution control device 

PDW primary drinking water 

PP pyrophosphate 

PRB Powder River Basin 

PTYG peptone–tryptone–yeast extract–glucose 
xi 

PYG peptone–yeast extract–glucose 

RCRA Resource Conservation and Recovery Act 

SBLP serial batch leaching procedure 

SCR selective catalytic reduction 

SDA spray dryer absorber 

SGLP synthetic groundwater leaching procedure 

SOx sulfur oxides 

SO2 sulfur dioxide 

SPME solid-phase microextraction 

TCLP toxicity characteristic leaching procedure 

UND University of North Dakota 

UNR University of Nevada–Reno 

WVWRI West Virginia Water Research Institute 
xii 

MERCURY AND AIR TOXIC ELEMENT IMPACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION

EXECUTIVE SUMMARY 

 The University of North Dakota Energy & Environmental Research Center (EERC) 

conducted a laboratory and field investigation designed to evaluate the impact of mercury and 

other air toxic elements (ATEs) on the management of coal combustion by-products (CCBs). 

Key objectives were: 

• To determine the release potential of mercury and other selected ATEs from CCBs 

under specific environmental conditions. 

• To increase the database of information on mercury and other ATE releases for CCBs. 

• To develop comparative laboratory and field data. 

• To develop appropriate laboratory and field protocols to measure mercury and ATE 

releases from CCBs. 

 The multiyear study comprised several tasks, including laboratory methods development 

and selection, sample selection, sample characterization, laboratory release experiments, and 

measurement of mercury releases at a field site. 

 Laboratory tasks were designed and performed to address fundamental issues critical to 

determining the release of these constituents over the life cycle of CCBs in a variety of 

management scenarios. Release mechanisms addressed included: 

• Direct leachability of air toxic constituents from CCBs. 

• Vapor release of mercury from CCBs at ambient and elevated temperatures. 

• Biologically induced leachability and vapor release of mercury and other ATEs from 

CCBs. 

 Experimental 

 The experimental component of this project was important to accomplishing the work in 

this project since standard experimental protocols were not available at the time the project was 

initiated. Throughout the duration of the project, the research staff continued efforts to select and 

develop experimental protocols to simulate mercury and ATE releases under varying conditions 

and the analytical methods required to quantitate those releases. 

 Multiple leaching procedures were used to evaluate the potential mobility of mercury and 

other ATEs from the CCBs obtained for use in the project. Development of laboratory methods 
xiii 

to evaluate vapor-phase mercury releases under ambient and microbiologically mediated 

conditions continued throughout the project. Methods for quantitation of mercury collected from 

vapor-phase release experiments and field sampling were developed in parallel with those 

efforts. Analytical tools were also used to quantitate and speciate organomercury compounds 

primarily in vapor-phase releases from laboratory experiments. 

 Using the experimental protocols selected and developed, a large number of samples were 

evaluated to determine if there was potential for mercury and other ATEs to be released from 

those samples under conditions to which CCBs would be expected to be exposed in typical 

management activities. 

 Results 

 The results of this project were dependent on the careful selection and collection of 

samples for inclusion in the laboratory evaluations performed for this task. Identification and 

basic characterization information was collected and generated for the samples in the final 

sample set, which included several paired sample sets that were obtained at facilities that were 

demonstrating mercury emission control technologies. A paired sample set included a baseline 

sample collected under normal operating conditions and one or more test samples collected 

during demonstration of mercury control. A summary of the samples included in the study is 

shown in Table ES-1, and the paired sample sets are listed in Table ES-2. 

 Total mercury content was determined for nearly all samples in the sample set, and total 

elemental concentrations of the ATEs evaluated in this project (arsenic, cadmium, chromium, 

lead, nickel, and selenium) were determined for a large number of samples in the sample set. 

When mercury emission controls were in place, fly ash samples exhibited consistently higher 

total mercury concentrations. For some fly ash samples collected from systems with mercury 

emission controls in place, selenium was also elevated. This was most noteworthy in samples 

collected from mercury emission control systems where activated carbon (AC) was injected after 

the primary particulate control device. It was determined that the total concentrations of all 

elements, except mercury and selenium, were similar for fly ash and for flue gas desulfurization–

spray dryer absorber (FGD–SDA) material samples generated with and without mercury 

emission controls present. While no wet FGD material samples were collected from systems with 

mercury emission controls in place, the total elemental data for these materials indicated 

significantly higher levels of most ATEs in wet FGD material + fly ash (fixated wet FGD 

material). 

 The moisture content and loss on ignition (LOI) of solid CCBs were determined as part of 

the fundamental characterization. It has long been known that LOI is not a direct measurement of 

carbon content of fly ash; however, when AC is being added to fly ash, as with most test samples 

evaluated in this project, the LOI value typically reflected the amount of carbon present in a fly 

ash sample. Fly ash samples collected from mercury control technology testing exhibited LOI 

values ranging from 0.59% to 24.4%. Fly ash without mercury control had LOI ranging from 

0.22% to 21.2%. These ranges were similar, and the highest LOI values were atypical of the 

samples evaluated, although the fly ash samples collected in demonstrations where the AC was 
xiv 

Table ES-1. Summary of Project Samples and Fundamental Characterization Data

Coal Type 

Type of SO2

Control 

No. of 

Samples 

Sample Type 

with Hg Control 

Description 

24-hour pH 

Range 

LOI 

Range, % 

Total Hg 

Concentration 

Range, μg/g 

Bituminous No SO2 control 21 Fly ash 5.52–12.65 0.47–21.2 <0.01–0.685 

 

6 

Fly ash + AC 

(post-primary 

PCD1

) 3.99–9.20 12.6–24.4 0.742–120 

 

2 

Fly ash + AC 

(pre-primary 

PCD) NT2 NT NT 

 Wet Mg- 

 enhanced lime 2 FGD gypsum 7.75–7.88 1.22–1.92 0.032–0.044 

 Wet limestone – 

 forced 

 oxidation 3 FGD gypsum 7.72–7.95 1.60–2.26 0.043–0.103 

 Wet limestone – 

 nonoxidized 3 FGD filtercake 7.70–7.88 4.20–6.19 0.162–0.305 

 3 Fixated FGD 10.50–12.43 3.11–4.17 0.136–0.249 

Subbituminous No SO2 3 Fly ash 12.27–12.56 0.32–1.08 0.261–1.22 

 

4 

Fly ash + AC 

(pre-primary 

PCD) 10.95–11.90 2.28–4.14 1.09–5.81 

 SDA 1 FGD–SDA 12.22 2.07 0.105 

Lignite No SO2 control 13 Fly ash 10.50–12.74 0.22–7.48 <0.01–0.878 

 

8 

Fly ash + AC 

(post-primary 

PCD) 10.52–11.41 0.59–13.2 0.147–64.5 

 

6 

Fly ash + AC 

(pre-primary 

PCD) 11.86–12.61 0.96–4.21 0.225–12.7 

 

3 

Fly ash + EA3 + 

AC (pre-primary 

PCD) 12.29–12.77 1.04–2.49 0.287–0.640 

 1 Fly ash + EA 11.77 1.70 0.717 

 SDA 3 FGD–SDA 12.50 0.95–12.5 <0.01–2.55 

 SDA 

1 

FGD–SDA + 

EA + AC (preSDA) 12.54 1.12 0.332 1

 Pollution control device. 

2

 Not tested.

3

 Enhancing agent.
xv 

Table ES-2. Paired Samples and Fundamental Characterization Data 

ID No. Sample Type 24-hour pH LOI, % Hg, μg/g 

02-070 Fly ash 8.50 5.87 0.194 

02-069 Fly ash + AC (post-primary PCD) 8.43 12.60 0.742 

02-072 Fly ash 8.83 5.29 0.163 

02-071 Fly ash + AC (post-primary PCD) 8.63 17.22 0.975 

03-061 Fly ash 12.56 1.04 0.578 

03-060 Fly ash + AC (pre-primary PCD) 11.90 2.38 1.86 

04-035 Fly ash 12.74 2.46 0.159 

04-036 Fly ash + EA + AC (pre-primary 

PCD) 

12.77 2.33 0.287 

05-001 Fly ash 12.51 0.90 <0.01 

05-003 Fly ash + EA + AC (pre-SDA) 12.29 1.04 0.565 

05-005 Fly ash 11.57 1.29 0.431 

05-017 Fly ash + EA 11.77 1.70 0.717 

05-038 Fly ash 11.73 0.22 0.104 

05-013 Fly ash + AC (post-primary PCD) 11.33 13.2 39.0 

05-023 Fly ash + AC (pre-primary PCD) 12.00 3.84 12.7 

05-024 Fly ash + AC (post-primary PCD) 11.41 9.45 35.9 

05-025 Fly ash + AC (pre-primary PCD) 11.99 3.19 12.6 

05-040 Fly ash + AC (post-primary PCD) 11.36 9.68 44.5 

06-001 Fly ash + AC (post-primary PCD) 11.37 11.6 64.5 

05-002 Fly ash + FGD–SDA 12.50 0.95 <0.01 

05-004 Fly ash + FGD–SDA + EA + AC (preSDA) 12.54 1.12 0.332 

injected after the primary PCD had the highest LOI values. For that type of ACI (activated 

carbon injection), a portion of the fly ash produced is collected in the PCD, and a typically small 

amount of fly ash that passes through the PCD remains in the flue gas stream to the point of ACI, 

resulting in a higher AC content in the fly ash + AC stream. For FGD–SDA samples, the LOI is 

likely dependent on the LOI of the fly ash that is incorporated into the FGD–SDA final byproduct material. 

 In an effort to learn more about the impact of carbon forms on mercury capture and 

potential release, an evaluation of the carbon forms present in several fly ash samples was 

performed. The three major morphological carbon forms are inertinite, isotropic coke, and 

anisotropic coke, and each exhibits distinct and predictable physical properties. The reactivity 

series of these carbon forms is: 

 anisotropic coke > isotropic coke > inertinite 

 Fly ash samples with AC present contained more reactive carbon forms, indicating that the 

presence of high-sorbing carbon forms can be an indicator of elevated mercury in fly ash 

samples and that AC contains these high-sorbing carbon forms. 
xvi 

 The pH of all samples of sufficient quantity was determined, and since the pH of a material 

can influence the leaching profile and may impact the performance in certain utilization 

scenarios, including bulk placement in engineered fills, several pH measurements were made to 

develop the most accurate pH data possible. 

 On review of pH data by coal type, the following observations were made: 

• Eastern bituminous fly ash samples exhibited a wide range of pH values in all tests. 

This range was greater in the fly ash samples without AC than with AC. 

• The South American and western bituminous fly ash sample pH ranges were narrower 

and more similar to those of subbituminous and lignite fly ash samples than eastern 

bituminous fly ash samples. All fly ash + AC (pre-primary PCD) pH values for the 

South American bituminous, subbituminous, and lignite samples in the project were 

similar. 

• For some fly ash samples, the pH changed significantly over time. 

 The pH development data are interesting because pH is a primary factor in leachability and 

an indicator of the potential for secondary hydration phases to impact leachability and 

engineering performance. These data suggested that pH measurements for CCBs should include 

an equilibration time of at least 24 hours. The pH values reported for all FGD–SDA samples fell 

within a narrow range regardless of the presence of AC. The pH for these samples is primarily a 

result of the presence of unreacted sorbent, which is present as calcium hydroxide. Calcium 

hydroxide has a pH of 12.4, which is very similar to the pH values measured in the FGD–SDA 

samples. The ranges of pH values of FGD materials and liquids were acidic to near-neutral pH, 

with the exception of the fixated wet FGD materials. 

 The release of constituents found in CCBs is most likely to occur through exposure to 

water or direct leaching. Laboratory leaching was performed using multiple tests (toxicity 

characteristic leaching procedure [TCLP, U.S. Environmental Protection Agency Method 1311], 

synthetic groundwater leaching procedure [SGLP], and long-term leaching [LTL] with 30- and 

60-day equilibration periods) on a large number of the samples assembled for this project. 

Mercury and other ATEs were determined on leachates. The fly ash leaching data are included in 

Table ES-3. 

 Leaching results indicated that mercury is not readily leachable from fly ash, fly ash + AC 

and/or EA, FGD–SDA samples, and wet FGD materials. Most samples had leachate mercury 

concentrations below the 0.01-μg/L analytical method reporting limit. Short-term (18-hour 

SGLP) leaching results from fly ash samples collected from systems without mercury emission 

controls in place are shown in Figure ES-1. Figure ES-2 shows the 18-hour SGLP mercuryleaching data for fly ash + AC and/or EA samples plotted against the total mercury content of the 

sample. Results of short- and long-term leaching for fly ash indicated that total mercury content 

did not correlate with leachate mercury concentrations. The results plotted in Figure ES-2 

indicated that the higher total concentrations of mercury associated with the presence of AC were 

stable and not readily released through leaching. 
xvii 

Table ES-3. Ranges of Leachate Results for Fly Ash, μg/L 

Element Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA + 

AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

As <2–336 <2–16.3 <2–15.2 46.3–95.9 8.1–842 

Cd <0.2–8.30 <0.2–1.49 <0.2–0.39 <0.3–2.68 0.85–2.46 

Cr 1.40–277 3.60–560 <2–134 182–211 17.3–680 

Pb <0.001–8.50 <0.001–3.00 <0.001–3.00 <2 <2 

Hg <0.01–0.325 <0.01–0.068 <0.01–0.061 <0.01–0.02 <0.01–0.07 

Ni <2–80.6 <2–23.1 <2–25.2 <2–2.8 <2–23.4 

Se <2–514 <2–147 <2–47.2 <4–97.0 45.2–8620 

pH 3.54–12.81 3.80–12.60 12.21–12.61 11.69–12.01 3.79–11.82 

Figure ES-1. Fly ash 18-hour SGLP leachate mercury plotted against total mercury content. 
xviii 

Figure ES-2 Fly ash + AC and/or EA 18-hour SGLP leachate mercury plotted against total 

mercury content.

 In leachate from FGD–SDA samples collected both with and without mercury emission 

controls in place, mercury was measured either at very low concentrations or was below the 

analytical reporting limit. As noted for fly ash, no correlation between the total and leachate 

mercury concentrations was observed. 

 Mercury leachate concentrations from the FGD materials were also generally low, but the 

18-hour SGLP results for the wet FGD filtercake and fixated wet FGD material were higher than 

the other wet FGD materials, FGD–SDA, and fly ash samples. Leaching of FGD gypsum 

resulted in the lowest mercury leachate concentrations of all the wet FGD material samples. 

 The laboratory leaching results all indicated that mercury is expected to be stable on CCBs 

when exposed to water. The potential for mercury to leach from CCBs is very low and is not 

expected to impact current fly ash management practices. 

 Selenium was the only ATE other than mercury identified as having increased total 

concentration in some fly ash + AC samples. Specifically, fly ash + AC samples where the AC 

was injected post-primary PCD exhibited an elevated total selenium content compared to the 

baseline for the single paired sample set of that type. Other fly ash paired samples that had the 

AC injected before the primary PCD did not exhibit this notable increase in total selenium 

content. In paired samples, selenium leaching was elevated in the short-term leachates with 

higher total selenium content; however, leachate selenium concentrations generally decreased in 

long-term leachates. 
xix 

 Arsenic leachate concentrations of fly ash + AC (pre-primary PCD), fly ash + EA + AC 

(pre-primary PCD), and fly ash + EA all were measured to be within the range reported for 

leachates from fly ash only. Total arsenic was not elevated in any samples with AC or EA 

present. For one paired fly ash and fly ash + AC (post-primary PCD) sample set, increased 

leachate arsenic concentrations were noted for several of the fly ash + AC test samples even 

though total arsenic concentrations were similar. Arsenic mobility from all FGD–SDA samples 

and wet FGD materials evaluated was low. 

 Leaching results for cadmium, chromium, lead, and nickel generally indicated that these 

elements had very low leachability in all sample types with and without mercury emission 

controls in place. 

 Ambient and elevated-temperature vapor-phase release of mercury was determined in 

laboratory experiments. Ambient-temperature experiments were performed in batches and were 

run for up to 200 days with mercury measurements taken at intervals. The data indicated that 

some samples released mercury and some samples sorbed mercury. An example of results from 

the ambient-temperature experiments is shown in Figure ES-3. 

 The sample set shown in Figure ES-3 included fly ash, fly ash + AC (pre-primary PCD), 

and FGD–SDA samples from eastern bituminous, Powder River Basin (PRB) subbituminous, 

and lignite coal. One paired sample set with a baseline fly ash (03-060) and a fly ash + AC test 

Figure ES-3. Sample Set 1 (194-day) long-term ambient-temperature mercury release or sorption 

as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate 

sorption of mercury. Duplicate bottles are represented. 
xx 

sample (03-061) was evaluated. Additional experiments provided similar results with fly ash 

samples collected both with and without mercury emission controls in place exhibiting sorption 

of mercury more commonly than release. Over the duration of the experiments, the rate of 

mercury typically decreased for all fly ash samples. FGD–SDA and wet FGD materials typically 

released mercury, and wet FGD materials exhibited a different release profile than fly ash 

samples, releasing mercury at a higher rate and for a longer duration. Following extensive 

exposure to ambient air, some of the wet FGD material samples showed sorption of mercury. 

Release/sorption rates were extremely low for all samples evaluated. 

 Fly ash samples were evaluated for the real-time elevated-temperature release of mercury. 

Thermal desorption curves provided a comparative means of evaluating the elevated-temperature 

release of mercury. Fly ash samples subjected to the elevated-temperature regime typically 

generated either one or two mercury peaks, with four being the maximum number of peaks 

identified for fly ash. Mercury was released at temperatures ranging from 256° to 750°C. Some 

samples, predominantly eastern bituminous fly ash samples with a LOI greater than 3% or fly 

ash + AC (post-primary PCD), continued to show increasing mercury release at 750°C. As 

shown in the sample thermal desorption mercury curve (Figure ES-4), the first peak recorded 

was typically sharp and well defined. Following peaks, where recorded, tended to show slightly 

less definition and were usually broader, although the absorption could be higher. 

 Samples with AC were more difficult to evaluate for elevated-temperature mercury 

releases, but sorbents that contained other compounds, such as halogens or sulfur, also offered 

analytical challenges. While sample identifications did not always indicate the exact nature of the 

Figure ES-4. Typical two-peak mercury desorption curve for fly ash. 
xxi 

AC used, samples of this type were expected to produce a thermal curve containing multiple 

peaks. Multiple peaks were noted in a significant number of fly ash samples and were likely 

because of the presence of multiple mercury compounds in the samples. 

 Multiple project samples were evaluated for microbiologically mediated mercury leaching 

and vapor-phase release. These experiments were challenging to carry out because of the 

requirements to keep the microbes active, the presence of fungi, and analytical interferences. 

Higher vapor-phase releases of mercury were measured for both elemental and organomercury 

for all samples evaluated in systems under aerobic conditions compared to those with anaerobic 

conditions. FGD–SDA and wet FGD filtercake samples exhibited significantly higher vaporphase mercury release rates than the fly ash samples evaluated, and the FGD–SDA sample 

evaluated had the highest release rate of vapor-phase mercury. Methylation of mercury did 

predictably occur in the experimental systems, but the apparent rate and resultant concentrations 

of methylmercury were extremely small. 

 A field task was accomplished in two subtasks: 1) Evaluation of Vapor-Phase Mercury at 

CCB Disposal Sites and 2) Small-Scale Vapor-Phase Mercury Release from Soil–Ash Mixtures. 

 The first subtask of the field investigation task was performed at CCB management 

facilities associated with a lignite-fired power plant where materials were collected for laboratory 

characterization and in situ mercury fluxes were measured by two methods. Even though the 

substrates measured varied slightly between the two types of measurements, a comparison of the 

results indicated good agreement for total mercury flux relative to substrate type as noted in 

Table ES-4. 

 An evaluation of the impact of the interaction between soil and CCBs on mercury release 

from CCBs was also performed on mixtures of 20% CCB addition to a soil–peat moss sample. 

Elemental mercury and organomercury release measurements were obtained on several samples 

and compared to a soil sample. The CCB–soil mixtures generally exhibited low levels of 

elemental mercury release, while the soil–peat moss sample (only one data point) sorbed 

elemental mercury. CCB–soil mixtures containing samples that had AC present released lower 

percentages of elemental mercury than those without AC present. On average, the samples with 

Table ES-4. Total Mercury Field Flux Results Comparisons 

EERC Measurements 

University of Nevada, Reno (UNR) 

Measurements 

Wet FGD Material + Mill Rejects 

> Stabilized Wet FGD Material (with fly ash) 

> Fly Ash 

> Wet FGD Material 

> Natural Grasslands (background soil) 

> Vegetated Fly Ash with Soil Cover 

> Bottom Ash/Mill Rejects + Wet FGD 

Material (sample not evaluated by UNR) 

Wet FGD Material + Mill Rejects 

> Stabilized Wet FGD Material (with fly ash) 

> Fly Ash 

> Agricultural Land (sample not evaluated by 

the EERC) 

= Wet FGD Material 

> Vegetated Fly Ash with Soil Cover 

> Natural Grasslands (background soil) 
xxii 

AC present released mercury an order of magnitude lower percentage than the sample from a 

similar coal source without AC. However, the measured elemental mercury release rate (pg 

mercury/g mixture/day) was higher for the fly ash + AC (post-primary PCD) samples. The 

results indicated that more organomercury was released from four of 13 replicate CCB–soil 

mixture bottles than from the bottle containing only the soil–peat moss sample. All 

organomercury releases were low. Again, the samples with AC generally exhibited a lowerpercentage release of organomercury than those without AC present, although the difference was 

not as consistent as that observed for elemental mercury releases. 

CONCLUSIONS 

 Conclusions drawn for the extensive laboratory and field work performed under this 

project can be summarized as follows: 

• Results for baseline fly ash or FGD–SDA and test samples with AC indicated that total 

mercury content was higher in the test samples. 

• The total selenium content was higher for the fly ash samples + AC (post-primary PCD) 

test samples than the baseline fly ash. 

• Total concentrations of arsenic, cadmium, chromium, lead, and nickel were similar for 

all fly ash samples and for FGD–SDA samples collected from systems with or without 

mercury emission controls in place. 

• Direct leaching tests indicated that mercury was not readily leached from fly ash or 

FGD materials. Leachate mercury concentrations were below the 0.01-μg/L analytical 

reporting limit for most samples evaluated. 

• Mercury leachate concentrations did not correlate to total mercury concentrations. 

• When exposed to ambient-temperature air in laboratory experiments, fly ash samples 

either released or sorbed small amounts of mercury. Samples containing unburned or 

AC tended to sorb mercury in ambient-temperature vapor-phase experiments. 

• Laboratory data indicated that the potential for ambient-temperature vapor-phase 

mercury releases from CCBs are unlikely to impact atmospheric mercury loading. 

• Mercury was not released to the vapor phase at temperatures below 250°C in elevatedtemperature experiments, but for most samples, 100% of the mercury on the CCB was 

released by 750°C. 

• Under microbiologically mediated conditions, only very low levels of elemental and 

organomercury were released in the vapor phase and leachate, although more elemental 

mercury was released. 
xxiii 

• Field experiments at a lignite CCB disposal site indicated low-level vapor-phase 

releases of mercury, as was generally noted in laboratory experiments for lignite fly ash 

samples. Releases from FGD materials were noted both in laboratory and field 

measurements. 

• Laboratory methods were developed to evaluate the potential for mercury releases 

under several release mechanisms. 
1 

MERCURY AND AIR TOXIC ELEMENT IMPACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION 

1.0 INTRODUCTION 

 Research has been under way for many years at the Univeristy of North Dakota (UND) 

Energy & Environmental Research Center (EERC) and elsewhere to evaluate the environmental 

performance of coal combustion by-products (CCBs) from coal-based combustion systems 

(ADA-ES, Inc., 2003; Carey et al., 1999; Energy & Environmental Research Center, 2005; 

Gustin and Ladwig, 2004; Hassett, 1994; Hassett and Heebink, 2002, 2007; Hassett et al., 2002, 

2003, 2004, 2005; Heebink and Hassett, 2002; Heebink et al., 2004, 2006; Hower et al., 2004; 

Keating and Chaisson, 1999; Laudal et al., 2000, 2001; Pavlish, 1999; Pflughoeft-Hassett et al., 

1996, 2004; Sanchez et al., 2006; Schwalb and Withum, 2003; Xin et al., 2006). A majority of 

this work has focused on the mobility of trace constituents from CCBs into the environment 

when these materials are beneficially used, especially when they are used in soil stabilization, 

engineered fill, or mine reclamation applications. Much of this work has been driven by the 1970 

Clean Air Act (CAA), which brought significant changes to the federal air quality program 

requiring the U.S. Environmental Protection Agency (EPA) to establish national air quality 

standards as well as national standards for significant new pollution sources and for all facilities 

emitting hazardous substances. The regulation of CCBs has been closely tied to environmental 

regulation of coal-fired power plants in the United States. Particulate control, flue gas 

desulfurization (FGD), and strategies to reduce nitrogen oxide emissions have all influenced the 

type and characteristics of CCBs being produced. The characteristics and performance of CCBs 

were evaluated under a mandate from EPA, and as a result, a final regulatory determination was 

made by EPA for fly ash, bottom ash, boiler slag, and FGD material, which became effective 

September 2, 1993. The rule stated that regulation of CCBs generated by coal-fired electric utilities 

and independent power producers as hazardous waste is unwarranted and that the materials will 

remain exempt from regulation as a hazardous waste under the Resource Conservation and 

Recovery Act (RCRA). This determination was upheld in a second EPA report in 1999, which 

focused on the management of fluidized-bed combustion wastes, low-volume wastes, pyrites, and 

comanaged wastes for which EPA determined that these materials would continue to be exempted 

from regulation under Subtitle C for hazardous wastes. 

 Significant work was performed and data reviewed for the 1993 and 1999 EPA 

determinations on CCBs. Review of those data indicated that the information on mercury in 

CCBs and its potential to be released into the environment was limited because the standard 

analytical methods used were generally not sensitive enough to measure mercury in CCBs or 

CCB leachates. This lack of quantitative data on the mercury content of and release from CCBs 

coupled with the understanding that coal-based power plant mercury emissions would likely be 

regulated in the future and that mercury emission control strategies would likely impact the 

character and behavior of the CCBs provide the motivation for the work undertaken in this 

project. 

 The scope of work was developed to provide data on the environmental acceptability of 

CCBs produced in systems with conventional and advanced emission controls by evaluating the 
2 

release of air toxic elements (ATEs) from CCB samples under controlled laboratory conditions 

and in select utilization and disposal field settings. 

 It was the goal of the project to compare the mercury and ATE release data generated from 

CCBs as currently produced and produced with advanced emission controls in place. The 

comparative data would provide a better understanding of the environmental performance of 

CCBs potentially to be generated with mercury emission controls in place. The project included 

work to: 

• Provide comparative information on CCBs from systems with various emission 

controls, which will aid utilities in selecting emission control technologies consistent 

with existing CCB management plans. 

• Develop scientifically sound experimental protocols for determining air toxic releases 

from CCBs based on CCB properties and management scenarios. 

• Provide information to the state and federal agencies that regulate disposal and 

utilization options. 

 Laboratory tasks addressed three areas: 1) direct leachability of air toxic constituents from 

CCBs, 2) vapor release of mercury from CCBs at ambient and elevated temperatures, and 

3) microbiologically induced leachability and vapor release of Hg and other ATEs from CCBs. A 

field task addressed mercury release at CCB management sites. The laboratory tasks were 

accomplished in conjunction with development of reliable methods to determine the release of 

ATEs from CCBs. While laboratory leaching has long been used to evaluate the mobility of 

various constituents from CCBs, the evaluation of vapor-phase transport and microbiologically 

mediated releases of ATEs required continued method development throughout most of the 

project. Development and use of appropriate methods to develop a project data set on currently 

produced CCBs and CCBs produced under experimental/simulated conditions provided an 

opportunity for the CCB industry to become aware of the potential impacts of mercury emission 

technologies on the CCBs produced, the expected environmental performance, and impacts to 

current CCB management strategies. 

 On initiation of this project, it was hypothesized that if CCBs as currently produced and 

from systems with proposed mercury emission control systems in place were found to exhibit 

comparable environmental performance, standard management scenarios could continue to be 

employed and CCB utilization could be expected to increase even after implementation of 

mercury emission controls. It was not the focus of this project to evaluate the impact of specific 

sorbents on the engineering performance of CCBs; however, over the course of this project, the 

EERC and others (Heebink et al., 2006; Lockert et al., 2005; ADA-ES, Inc., 2003; Gasiorowski 

et al., 2003) did find that the presence of activated carbon (AC) in fly ash is expected to impact 

the use of fly ash in concrete because of the reactivity of the AC and interaction with chemical 

admixtures used in concrete. 

 The presence of Hg and other ATEs in CCBs has raised concern by state regulatory 

agencies (Federal Register, 2000) and citizen groups about the potential environmental stability 
3 

of these elements under disposal and utilization conditions. This project has addressed the 

technical aspects of that concern, and it is important that the results of this study be 

communicated with the CCB industry, the regulatory community, and other stakeholders. The 

project results are expected to allow CCB managers and marketers to better evaluate 

management options for CCBs that may be produced after implementation of mercury emission 

controls. The data can also serve to aid in the selection of mercury emission controls for those 

CCB producers that manage their CCBs primarily through marketing. 

2.0 BACKGROUND 

 Recent projections from the Energy Information Administration indicate that U.S. demand 

for energy will increase from 97.3 quadrillion to 130.1 quadrillion Btu between 2001 and 2020, 

reflecting an annual growth rate of 1.5%. By 2025, total energy consumption is projected to 

reach 139.1 quadrillion Btu (Energy Information Administration, 2004). Fossil fuel combustion, 

including the burning of coal, natural gas, or oil, provides about 85% of the present energy 

production in the United States. Of this amount, over 50% is provided by coal-fired utilities 

(Energy Information Administration, 2004). As a result of energy production from coal, CCBs 

are generated, and CCBs, as produced in the United States, are primarily a result of emission 

control technologies installed to meet emission regulations. 

 Emission regulations first mandated reduction of particulate matter released to the 

atmosphere by utilities, which required utilities to install collection devices for generated fly ash. 

Later emission regulations significant to CCB production mandated limits on sulfur oxide (SOx) 

emissions. As a result, utilities using high-sulfur coal could change coal sources, resulting in a 

different by-product character or scrub the flue gas using sorbents to remove the SOx gases. The 

result of FGD was high volumes of spent FGD sorbent material. There is a wide range of FGD 

technologies, so FGD materials have broadly varied characteristics but generally contain high 

concentrations of calcium and sulfur. Currently, utilities are responding to regulations placing 

limits on nitrogen oxide (NOx) emissions, which also impacts the character of CCBs, including 

potentially increasing the amount of unburned carbon in fly ash or adding ammonia to the fly 

ash. Issues related to ATEs, including mercury, are currently under technical and regulatory 

scrutiny. 

 Figure 2-1 includes an excerpt from an EPA Fact Sheet entitled “EPA Proposes Options 

for Significantly Reducing Mercury Emissions from Electric Utilities,” in which some of the 

concerns about mercury are summarized. On December 14, 2000, EPA announced that it would 

regulate mercury emissions from coal- and oil-fired electric utility steam-generating power 

plants (Federal Register, 2000); propose regulations by December 15, 2003; and finalize 

regulations by December 15, 2004. On December 15, 2003, EPA signed the Utility Mercury 

Reductions proposal, which seeks comments on two approaches for reducing mercury by up to 

nearly 70%. On March 15, 2005, EPA issued the first federal rule to permanently cap and reduce 

mercury emissions from coal-fired power plants (a power plant is defined as an electrical 
4 

Figure 2-1. EPA information on mercury emissions (U.S. Environmental Protection Agency, 

2003). 

generating facility that provides >25 MWe). The rule is a market-based cap-and-trade program 

(CAA Section 111) and is similar to the program in place for sulfur dioxide (SO2). The rule is to 

be administered in two phases. The first phase places a cap of 38 tons per year of mercury 

beginning in 2010. The second phase sets a final cap of 15 tons by 2018. Coal-fired power plants 

currently emit about 48 tons per year; therefore, the reduction in mercury emissions will be 21% 

and 69%, respectively. 

 The reduction of emissions at coal-fired power plants has historically impacted the 

quantity and character of resulting CCBs, and with changing quantities and characteristics, the 

management and associated costs have also been impacted. One of the most noteworthy 

industrywide changes occurred when FGD systems were installed in the 1980s and large 

volumes of FGD materials were produced and required management. The removal or reduction 

of mercury emissions at coal-fired power plants also has high potential to impact CCB 

management because several proposed mercury emission control technologies involve the use of 

solid sorbents that will likely be introduced in the flue gas and collected with the fly ash. Other 

candidate emission control technologies focus on increasing the mercury sorbed on FGD 

materials. These mercury emission control technologies will impact the mercury content of 

CCBs. The question that this project was designed to answer is, Will the changes in CCBs 

associated with mercury emission controls change the management options for those CCBs as 

they relate to the potential release of mercury? The U.S. Department of Energy (DOE) National 

Energy Technology Laboratory (NETL) (2007) evaluated the cost of activated carbon injection 

(ACI) mercury control and reported that the incremental costs increased by a fraction of 1.5– 

3 when including impacts to CCBs in addition to implementation costs. DOE NETL reported 

costs for seven different power plant case studies, and when costs of impacts to CCBs were 
5 

included in the economic evaluation, four case studies had costs exceeding DOE’s cost target of 

$45,000/lb Hg removed. 

 Since the large volumes of CCBs produced annually in the United States are managed 

either by disposal or utilization, the design of various tasks in this project focused on simulating 

potential behavior of CCBs in environments where they are typically managed. Examples of 

utilization scenarios include: 

• The use of fly ash in concrete, soil stabilization, or fills that could be exposed to natural 

waters or to microbial action. 

• The use of FGD gypsum in wallboard, where it may be exposed to high temperatures in 

production or to natural water under disposal. 

• The use of fly ash in cement clinker production, where it would be exposed to 

extremely high temperatures. 

• The use of FGD gypsum or fly ash as an agricultural soil amendment or mine fill, where 

it would be exposed to natural water and, potentially, microbial action. 

 In order to adequately address the potential for release of mercury from CCBs, sorbents, 

and combinations, release mechanisms that must be evaluated include leaching, elevated- and 

ambient-temperature vapor-phase releases, and microbiologically mediated releases. The EERC 

initiated research on the potential release of mercury from CCBs in 1999 and found that methods 

for evaluating the release of mercury from CCBs using these mechanisms were not documented 

in the scientific literature, with the exception of leaching. As a result, the EERC initiated a 

program under EPA’s Center for Air Toxic Metals® and the Coal Ash Resources Research 

Consortium® (CARRC®) to develop laboratory methods that would provide information on the 

potential for CCBs to release mercury and other ATEs under conditions associated with the 

proposed release mechanisms of direct leaching, direct ambient- and elevated-temperature vaporphase release, and microbiologically mediated leaching and vapor-phase release. 

3.0 OBJECTIVES 

 The goal of the proposed effort was to evaluate the impact of mercury and other ATEs on 

the management of CCBs. Supporting objectives are to 1) determine the release potential of 

selected ATEs, including mercury and arsenic, from CCBs under specific environmental 

conditions; 2) increase the database of information on mercury and other ATE releases for 

CCBs; 3) develop comparative laboratory and field data; and 4) develop appropriate laboratory 

and field protocols. 

 The specific mechanisms of ATE releases evaluated were leaching releases, vapor releases 

to the atmosphere, and biologically induced leaching and vapor releases. 
6 

4.0 EXPERIMENTAL 

4.1 Literature Search 

 The literature search task was designed originally to allow the preparation of an annotated 

bibliography that included literature on the following topic areas: 

• Mercury and other ATE content of CCBs 

• The mobility/stability of those elements from/on CCBs 

• Emerging mercury control technologies, especially as they would potentially impact the 

characteristics or composition of CCBs 

 In the first project year, it was agreed by project sponsors and researchers that the use of an 

online database to store and retrieve the assembled documents would have greater value to the 

project, so the approach was modified to enable the development of an online database for the 

literature collected, allowing project sponsors access to all information gathered. 

 Throughout the duration of the project, the project team collected and reviewed various 

documents that pertained to mercury and other ATEs. The documents were gleaned from 

journals, symposium and conference proceedings, news articles, and several other sources. Both 

national and international documents were collected. 

4.2 Analytical Methods Selection 

 To evaluate the potential for release of mercury and other ATEs from CCBs, appropriate 

methods were required, including both experimental methods and analytical methods. This task 

focused on the selection and continued development of experimental protocols to simulate Hg 

and ATE releases under varying conditions and the analytical methods required to quantitate 

those releases. 

4.3 Sample Identification and Selection 

 Sample identification and selection ranked high in importance in conjunction with other 

critical components of the project because the results of laboratory tests and experiments are 

sample-specific. In order for laboratory results to be valid and relate to real-world applications, 

CCBs evaluated must be representative of those expected to be generated at full-scale coal-fired 

power plants. 

 The objective of this task was to identify, select, and obtain CCB samples of appropriate 

type, quality, and quantity for use in the laboratory evaluation of the stability of mercury and 

other ATEs. 
7 

4.3.1 Sample Prioritization 

 A sample prioritization was developed based on the behavior of mercury. As shown in 

Figure 4-1, mercury is a highly volatile element that, along with fluorine and chlorine, is 

expected to be essentially 100% associated with the flue gas and carried out of the stack. For this 

reason, mercury that may be associated with CCBs has the greatest likelihood of being 

associated with the fly ash or FGD materials. The temperatures at which bottom ash and boiler 

slag leave the combustion system are too high for mercury to associate with these materials, so 

researchers made the recommendation to project sponsors that these materials be excluded from 

the sample set, and the recommendation was accepted. 

 Sample identification and selection activities resulted in the preparation of a target list of 

samples expected to provide data from which conclusions and generalizations can be drawn over 

the duration of the project. Sample collection was a major and ongoing task. 

 Samples of fly ash and FGD material from systems with conventional combustion and 

emission control technologies were relatively simple to access through the EERC’s CCB 

research program and contacts. These samples generally were collected and submitted as 

samples for typical utilization applications. Most of these samples were collected as composites 

or from locations within the plant where “as-managed” samples could be accessed. These 

samples were most likely to represent the materials that are utilized or sent for disposal and 

provided the most reliable results for real-world comparisons. 

Figure 4-1. Categorization of trace elements associated with coal ash based on volatility.
8 

 As-managed samples were generally not available from demonstrations of mercury 

emission controls. Some of the mercury emission control demonstrations were performed on 

pilot-scale equipment and some were performed on slipstreams at full-scale power plants. 

Samples from these types of systems had the disadvantage of not being collected with typical 

pollution control devices (PCDs). In cases where mercury emission control was demonstrated at 

full-scale power plants and collected with existing full-scale PCDs, the samples were generally 

collected from specific fields within the electrostatic precipitator (ESP). 

 At the Year 1 Project Review Meeting, project sponsors and researchers discussed the 

advantages and disadvantages of using samples from mercury emission control demonstrations in 

this effort. In cases where the baseline and mercury control samples were collected at the same

location, the samples provided comparative data. However, these data cannot be directly

compared to data generated on as-managed samples. Hower et al. (2004) presented information

on total mercury content in samples of fly ash collected at different locations at one power plant,

as noted in Figure 4-2. The data indicate that samples from a single location in a full-scale power 

plant are unlikely to represent the mercury content in the associated as-managed sample. Similar 

variations may be expected for other ATEs. 

4.3.2 Sampling and Storage Procedures 

 The issue of obtaining and maintaining a high-quality sample for laboratory investigations 

is common across numerous scientific disciplines. In the area of CCB research and testing, some 

sampling and sample storage issues are critical to performing laboratory work that provides 

information that can be translated to the real-world management of CCBs whether that is 

utilization or disposal. These issues can be more or less important based on the type of CCB 

under consideration. Fly ash and FGD materials, have different sampling and storage 

requirements. A description of each of these materials follows: 

• Fly ash is homogeneous on the macroscale yet heterogeneous on the microscale. 

Further, fly ash can vary with changes in the operation of the plant over the course of 

hours, days, weeks, or months. For this reason, composite samples are generally 

recommended when fly ash is sampled. For most laboratory evaluations, fly ash is 

collected from a storage facility, a disposal site, or a truck or train car at the point of 

delivery. These samples, referred to as “as-managed,” are generally representative of 

the sample to be used or disposed of. Fly ash samples collected from specific locations 

in the PCD are not considered representations of the bulk material that is used or 

disposed of. 

• FGD material is generally a high-sulfur material but can have varying physical and 

chemical characteristics based on the type of FGD system and material-handling 

protocols. Physically, FGD material can range from a very wet material to nearly dry. 

Generally, FGD materials to be characterized are usually collected after a dewatering 

step. This is especially true for FGD materials that are being evaluated for utilization 
9 

Figure 4-2. Mercury distribution in a power plant (Hower et al., 2004). 

 applications such as FGD gypsum for use in wallboard. The method of dewatering and 

collection can impact the chemical composition of the FGD material. FGD material that 

is destined for disposal may be collected either from a location referred to as the 

“blowdown” for the wet FGD systems or it may be collected at the point where it exits 

the transport system to the disposal site. In some instances, wet FGD material may be 

stabilized by the addition of fly ash or other reagents such as lime prior to use or 

disposal. In these cases, the added reagent may impact the chemical composition and 

behavior of the FGD material. FGD material from a spray dry absorber (SDA) system 

may have fly ash incorporated into the FGD material as part of the system. In selecting 

and collecting FGD material samples for laboratory evaluations, the sample should 

represent the material as-managed, and the laboratory personnel must be aware of 

special handling and reagents that may have been added. 

 Under ideal conditions, sample collection procedures followed ASTM (American Society 

for Testing and Materials) International C311 procedures. The standard defines grab samples as 

samples taken at prescribed intervals over a period of time and having a mass of at least 

4 lb. Grab samples can be combined to make a composite sample having a mass of at least 8 lb. 

According to ASTM C311, samples taken from bulk storage, railcars, or trucks may be taken by 

siphon tube during loading or by sampling tube from each railcar or truck. If the load is sampled 

at the point of discharge into a railcar or truck, the top 8 in. must be removed. 

 Dry material samples (fly ash–sorbent, spent sorbent, and FGD solids) of greater than 1 gal 

were homogenized to create a representative 2- to 4-L sample that is transferred into a glass jar 

with Teflon-lined cap to ensure sample integrity was maintained over the duration of the project. 

Liquid FGD samples were mixed thoroughly, and a 2- to 4-L aliquot was transferred to a glass 
10 

jar with a Teflon-lined cap. Liquid sample aliquots were stored under refrigeration (<4°C) until 

the testing was completed. Homogenized subsamples were stored in the laboratory for use 

throughout the project. Original containers were stored in a secure area. 

 Proper storage was important for maintaining the composition and integrity of the samples 

because the properties of the samples can change with time depending on the material 

characteristics. 

4.3.3 Sample Collection 

4.3.3.1 Sample Identification Form 

 In order to best categorize and interpret project results, information on the sample type, 

coal used, and system was needed. A sample identification form was developed that allowed 

each sample submitter to easily identify system and sample information. All sample submitters 

were given the sample identification form. The sample identification form was extremely useful 

in this effort because the same identification information is available for most project samples, 

facilitating data interpretation. A copy of the sample identification form is included in 

Appendix A. 

4.3.3.2 Confidentiality 

 Confidentiality of sample identity was discussed with sample submitters, and when 

requested, confidentiality agreements were signed. Each sample was assigned a project number, 

which was the primary identifier for all samples. Other identifying information has been 

provided by most sample submitters through the sample submission form. That information 

included submitter name, location and name of power plant or pilot- or bench-scale system, fuel 

type, plant configuration, and some operating information. All of these identifiers were kept 

confidential for this report. 

4.4 Chemical and Physical Characterization 

 The objective of this task was to characterize selected samples in order to understand the 

physical, engineering, and environmental performance of the materials and ensure that a cross 

section of fly ash and FGD materials was represented in the investigation. The chemical 

characterization included determination of bulk chemical composition (major, minor, and trace 

element constituents) with a focus on the mercury and identified ATEs. In addition to mercury, 

the ATEs included in the characterization and the overall study were arsenic, cadmium, 

chromium, lead, nickel, and selenium. Physical characterization included loss on ignition (LOI), 

moisture content, pH, and carbon forms measurements. Eh was measured in leachate samples 

from the microbiologically mediated release experiment where a liquid medium was used to 

promote microbial growth. Data developed in this characterization task were used to aid in 

interpretation of the results from release experiments. 
11 

4.4.1 Analytical Methods for Characterization and Release Experiments 

 Standard methods were selected and used for sample preparation and analyses where those 

were available and appropriate for the sample types, volumes, and matrices. Sample preparation 

and analysis methods were modified or developed as needed where standard methods did not suit 

the needs of the project. 

4.4.1.1 Total Mercury and Air Toxic Elements 

 The total mercury content of the majority of solid samples was determined using a direct 

mercury analyzer (DMA-80). Additionally, digestion followed by cold-vapor atomic absorption 

spectrometry (CVAAS) (EPA Method 7471) (U.S. Environmental Protection Agency, 2005a) 

was utilized. 

 The total concentrations of the other ATEs of arsenic, cadmium, chromium, lead, nickel, 

and selenium were determined using standard methods. Acid digestion was used on the CCB 

followed by detection using inductively coupled plasma–atomic emission spectroscopy (ICP–

AES) (EPA Method 6010B) (U.S. Environmental Protection Agency, 2005b) or ICP–mass 

spectroscopy (ICP–MS) (EPA Method 6020) (U.S. Environmental Protection Agency, 2005c). 

4.4.1.2 Total Bulk Chemical Composition 

 The major bulk composition, reported as percent oxides, was determined using x-ray 

fluorescence spectrometry. ASTM D4326-04 Standard Test Method for Major and Minor 

Elements in Coal and Coke Ash by X-Ray Fluorescence was used (ASTM International, 2004a). 

4.4.1.3 LOI and Moisture Content 

 Standard characterization techniques were used to measure LOI and moisture content. 

ASTM C311-04 Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans 

for Use in Portland-Cement Concrete was used (ASTM International, 2004b). 

4.4.1.4 pH 

 The pH of samples was determined using distilled water and/or 1 M KCl. The method 

employing 1 M KCl was required for many types of solid samples that exhibit a double electric 

layer that affects the determination of pH. For this task, 25 mL of 1 M KCl solution was mixed 

with 10 g of CCB, and the resulting pH was measured and recorded. As previously noted, the pH 

was also determined in slurry of distilled, deionized water. Where both methods were employed 

in this effort, it was noted that the pH values were similar. A comparison of these data for a 

relatively broad range of CCB types led researchers to conclude that it is not necessary to use 

1 M KCl in determining the pH of CCBs; therefore, remaining samples were evaluated using 

distilled, deionized water slurries. It is likely that the high concentration of total dissolved solids 

generated in the pH determination eliminated the double electric layer effect that requires the use 

of KCl solution in the determination of pH in other types of solid samples. It was found that for 
12 

some samples especially those containing added carbon, up to 24 hours of equilibration was 

required in order to obtain a stable and accurate pH reading. 

4.4.1.5 Carbon Forms 

 Dominant carbon forms were identified in a select group of project samples. The samples 

on which carbon forms were determined were prepared by mounting in epoxy resin. The sample 

was dispersed in the bottom of a 1-in.-diameter rubber cup mold. The epoxy was stained using 

Sudan black, which results in a high contrast between the particles of interest and the mounting 

medium. The surfaces to be analyzed were polished with incrementally smaller grits, with 1⁄4 μm 

being the final polishing grit used. The samples were then examined using a reflected-light 

microscope. 

4.4.1.6 Eh 

 Eh was determined using a platinum electrode with a standard reference electrode. 

4.4.1.7 Methods of Measurement Specific to Release Experiments 

4.4.1.7.1 Gold-Coated Quartz Traps 

 Gold-coated quartz mercury collection traps used to collect Hg from various release 

experiments were desorbed for analysis by heating to approximately 500°C, and the mass of 

mercury released was determined using double-gold amalgamation with atomic fluorescence 

(AF) detection. A Brooks Rand Model III cold-vapor atomic fluorescence spectrophotometer 

(CVAFS) was utilized for mercury concentration determination. Mercury peaks were recorded to 

allow quantitation using an integrator. 

4.4.1.7.2 Measurements of Mercury on Carbotraps 

 Supelco CarbotrapTM collection traps were also used in several release experiments and 

were analyzed for total mercury by heating to approximately 300°C, passing the released 

organomercury through a tube held at about 800°C, and collecting the mercury on a gold-coated 

quartz trap, which was analyzed as described above. 

4.5 Laboratory Evaluation of ATE Releases 

 Assembled samples were used in laboratory experiments focusing on specific release 

mechanisms of mercury and other ATEs. Primary release mechanisms are leaching, vaporization, 

and biologically stimulated leaching and vaporization. ATEs were evaluated including arsenic, 

cadmium, chromium, lead, mercury, nickel, and selenium for release through leaching. Vaporrelease experiments focused on mercury. 
13 

4.5.1 Direct Leaching 

 Methods for leachability were broadly available, but a review of leaching methods was 

required in order to ensure that reliable results would be generated. The appropriateness of 

individual leaching procedures is frequently debated, and selection of leaching procedures for 

this effort was a key activity under this task. The EPA Office of Research and Development 

(ORD) developed a standard leaching protocol for research related to mercury release from 

CCBs, and the EERC participated in discussions coordinated by EPA ORD in the development 

of that protocol. 

 Leaching is the most likely mechanism of transport of constituents from disposed or 

utilized CCBs contacted by water. Leaching is typically performed on CCBs to characterize them 

for management purposes. The leaching tests performed on the samples in this project were the 

toxicity characteristic leaching procedure (TCLP) (EPA Method 1311) (U.S. Environmental 

Protection Agency, 1992), the synthetic groundwater leaching procedure (SGLP), and long-term 

leaching (LTL) with 30- and 60-day equilibration periods (Hassett, 1998). TCLP was included 

because some regulatory groups continue to use TCLP results to determine whether a “waste” is 

hazardous. The SGLP–LTL was used because previous EERC work has shown it to yield 

scientifically valid results on CCBs including reactive CCBs (Hassett, 1994; Hassett et al., 

2005). 

 TCLP is a leaching procedure designed for the evaluation of leaching of wastes when 

codisposed in a sanitary landfill. Leaching with TCLP utilizes a 20:1 liquid-to-solid ratio, endover-end agitation at approximately 30 rpm, an 18-h equilibration time, and one of two 

extraction fluids. The extraction fluid used is dictated by the pH of the material being leached. 

Extraction Fluid 1, used when the pH is below 5, is prepared by adding glacial acetic acid and 

sodium hydroxide to reagent water, and has a fluid pH of 4.93 ± 0.05. Extraction Fluid 2, used 

when the pH of the material is above 5, is prepared by adding glacial acetic acid to reagent water, 

resulting in a fluid pH of 2.88 ± 0.05. 

 The SGLP batch-leaching procedure is a relatively simple test that follows many of the 

conditions of TCLP. The test utilizes a 20:1 liquid-to-solid ratio, end-over-end agitation at 

approximately 30 rpm, an 18-h equilibration time, and usually employs a leaching solution 

consisting of water from the site, water that has been prepared in the lab similarly to water likely 

to contact the CCB, or distilled, deionized water. When distilled water is used as the leaching 

solution for SGLP, the method is equivalent to the ASTM D3987 Standard Test Method for 

Shake Extraction of Solid Waste with Water (ASTM International, 2006). Distilled, deionized 

water was used in this effort. For the long-term component of this procedure, multiple bottles 

were set up and analyzed at different time intervals. A typical SGLP–LTL test might consist of 

18-h, 30-day, and 60-day equilibration times. Although 60 days is often not adequate to achieve 

complete equilibrium, it is generally long enough to determine the concentration evolution of 

individual parameters. The most important factor when performing LTL is to have at least three 

equilibration times to determine a true trend. A draft of the SGLP–LTL method prepared for 

consideration by ASTM is in Appendix B. 
14 

 For all leaching procedures, the solids were filtered from the leaching solution through a 

0.45-μm filter, the pH of the resulting leachate was measured, and the leachate was preserved 

with hydrochloric acid (HCl) for mercury determination and with nitric acid (HNO3) for 

determination of other trace elements. 

 Mercury leachate concentrations were determined using CVAAS and CVAFS. Other trace 

elements were determined using ICP–MS or graphite furnace atomic absorption spectroscopy. 

 The SGLP method was used preferentially for the project samples, and where TCLP was 

applied, SGLP was applied for comparative purposes. The SGLP short-term leaching procedure 

was applied to all samples, but for samples with a pH >10, the LTL option was also used. LTL 

provides the most valuable information when at least two long-term tests are run (30-day and 

60-day LTL or longer as recommended) and reported in conjunction with SGLP results. CCBs 

exhibiting a high pH have the potential to undergo hydration reactions that can change the 

leaching profile with time. The EERC documented the impact of ettringite formation on leachate 

concentrations of several elements that are frequently present in CCBs, such as arsenic, 

selenium, and boron. The elements that are most likely to be incorporated into the ettringite 

structure and exhibit a change in leaching profile with time are those that are present as 

oxyanions at high pH. Examples of leaching profiles of high-pH CCBs for some trace 

constituents commonly found in CCBs are shown in Figures 4-3 and 4-4. 

Figure 4-3. Example LTL results for boron.
15 

Figure 4-4. Indirect evidence of ettringite formation using SGLP and LTL (note: boron is on a 

secondary axis).

 In Year 2, the task was expanded to include participation in a DOE NETL informal 

interlaboratory round-robin experiment aimed at providing the industry with appropriate leaching 

procedures for CCBs. NETL sent a sample to all participating laboratories for evaluation. 

Samples were requested by the EERC from various utilities burning subbituminous or lignite 

coal to provide an additional fly ash sample for evaluation. Samples received were evaluated, 

and one reactive sample was selected for the experiments and sent to participants. Four leaching 

procedures including the 3-tier leaching protocol (Kosson et al., 2002), the serial batch leaching 

protocol (SBLP) developed by NETL, the SGLP and LTL with 30- and 60-day equilibration 

periods (Hassett, 1998), and the mine water leaching protocol (MWLP) proposed by the West 

Virginia Water Research Institute (WVWRI) National Mine Land Reclamation Center 

(NMLRC) (Ziemkiewicz, 2005) were part of the informal round-robin experiment. The SBLP 

and SGLP–LTL tests were performed on the two ash samples at the EERC. A 90-day 

equilibration period was included at the EERC for this study. 

4.5.2 Vapor-Phase Mercury Transport 

4.5.2.1 Long-Term Ambient-Temperature Release 

 In order to develop a method to evaluate the potential for release of mercury from CCBs at 

ambient temperatures, several preliminary decisions were made based on the practicality of 

performing this type of evaluation in the laboratory: 
16 

• Since most CCBs contain low concentrations of mercury, samples with relatively high 

concentrations of mercury would be used in experimental development and for initial 

measurements. 

• To facilitate evaluation of multiple samples over long duration, gold-coated quartz 

mercury collection traps would be used to collect mercury vapor over predetermined 

time periods, allowing for determination of total mercury released and rate of release. A 

dedicated mercury analyzer was not available for long-term real-time mercury release 

measurements. 

• In order to evaluate multiple samples with available equipment and instrumentation, 

released mercury was collected on analytical gold-coated quartz traps. 

• Low release of mercury was anticipated, so it was decided to expose a column of CCBs 

to low-mercury air rather than expose only the surface of a CCB to the ambienttemperature low-mercury air. 

 Using preliminary premises based on previous EERC work, 250-mL wide-mouth glass test 

containers with bonded Teflon liner caps were used. Two holes were drilled in the caps to 

accommodate a silicone tube for gas inlet and a Teflon outlet bulkhead fitting. The gas inlet tube 

extended only slightly into the container, while the outlet tube extended nearly to the bottom of 

the container. A shorter outlet tube situated above the sample was used for wet FGD material 

samples because air could not flow through the sample to the outlet below the sample surface. 

 Using these test containers, 75–200-g aliquots of CCB provided a column of material 

through which the low-mercury air could be transported. Breathing-quality air from a cylinder 

was passed through several sets of gold-coated quartz traps for mercury removal and admitted to 

each of the bottles through a gas distribution manifold that routed the gas through 0.25-mm-i.d. 

gas chromatography (GC) capillary tubing to each of the individual bottles. The pressure drop 

across the GC capillary tubing allowed for the regulation of airflow through each bottle by 

simply adjusting the length of tubing to each bottle. The length of tubing was a nominal 65 cm. 

This length of tubing, when pressurized to between 1 and 2 psig through a gas distribution 

manifold, provided a convenient means of regulating gas flow to approximately 2 cm3

/min. 

Because of the variability of particle sizes between different CCB samples, the sample with the 

initial highest gas flow was left with a 65-cm length of GC tubing, and other samples had their 

tubing lengths shortened until all samples had approximately the same flow rate. The air exiting 

the GC tubing was given a final scrubbing to remove mercury vapor using a gold-coated quartz 

trap just prior to entering the bottle containing the CCB. After entering the bottle, the air passed 

through the CCB and exited to a mercury collection tube containing two separate gold-coated 

quartz traps. The trap nearest the exit bulkhead fitting, or analytical trap, collected mercury 

released from the CCB and bottle. The second outlet, or top trap, was used to prevent mercury 

contamination from atmospheric mercury. This setup is illustrated in Figure 4-5. 

 The gold-coated quartz analytical trap nearest the exit bulkhead fitting was analyzed 

multiple times, with the most typical sampling scheme being one 7-day mercury vapor collection 
17 

Figure 4-5. Ambient-temperature mercury vapor release collection apparatus.

period followed by two consecutive 90-day mercury vapor collection periods. The gold-coated 

quartz analytical traps were evaluated according to the method described in the analytical 

method section. In order to determine the total mercury released over the duration of the 

experiment, the mercury results from all experimental time segments were combined, and the 

container blank was subtracted. The container blank was determined on the empty bottles used to 

hold the samples. 

4.5.2.2 Thermal Desorption at Elevated Temperature 

 Since mercury and mercury compounds are highly volatile, mercury release from CCBs 

was expected when they were exposed to elevated temperatures. Even mercury that is sorbed 

onto fly ash, FGD material, or sorbents developed to remove mercury in flue gas was expected to 

have high potential to be released if exposed to high enough temperatures. Instrumental and 

equipment constraints existed for the physical testing of elevated-temperature release of mercury 

from CCBs. These constraints included the following: 

• Furnaces available for the experimental apparatus could only achieve maximum 

temperatures of 750°C. 

• Fittings and connecting tubing needed to be heated in order to minimize the loss of 

mercury in the system. 
18 

• Gas flow to remove the mercury from the heated sample cell to the analytical cell 

needed to be constant. 

• Temperature ramping needed to be controlled and consistent between sample runs. 

• Detection limit of atomic absorption (AA)-determined sample size. 

 An apparatus was constructed as shown in Figure 4-6. The CCB sample was weighed into 

a quartz tube, with quartz wool used to keep the sample in place in the tube. Sample size varied 

from approximately 300 to 900 mg. The sample tube was placed into a small tube furnace 

capable of achieving a maximum of 750°C. A programmed temperature controller ramped the 

furnace from ambient to maximum temperature at 25°C per minute. In preliminary experiments, 

the maximum temperature achievable was 700°C, but an improved furnace was incorporated into 

the apparatus to increase the maximum to 750°C. A nitrogen gas flow of 5 cm3

/min was 

introduced into the tube furnace. As the mercury and mercury compounds desorbed from the 

CCB in the sample tube, the nitrogen flow carried them through the system to the electrically 

heated quartz analytical cell. The quartz analytical cell was operated at 800°C, allowing the 

detection of mercury compounds by thermally decomposing compounds to form elemental 

mercury, which can be detected by AA. The analytical cell at the top of the diagram was placed 

in the center-focused beam path of an AA spectrophotometer (AAS). A mercury hollow-cathode 

lamp was used as the light source, and the AAS detector was set to the 253.7-nm line for 

mercury. A Hewlett Packard 3395 integrator was used for data collection. Examples of thermal 

desorption curves generated with this method are shown in Figures 4-7 and 4-8. The integrator 

used standard algorithms to identify peaks and indicated the time of peak maximum, which is 

noted in Figures 4-7 and 4-8. 

Figure 4-6. Mercury thermal desorption apparatus.
19 

Figure 4-7. Typical thermal desorption curve for fly ash (peak time is noted in minutes for each 

peak recognized by the electronic integrator used for data collection).

Figure 4-8. Example of thermal desorption curve for an FGD material (peak time is noted in 

minutes for each peak recognized by the electronic integrator used for data collection).
20 

4.5.2.3 Mercury Speciation Method 

 It has been hypothesized that the mercury species associated with fly ash, FGD material, or 

carbon might be identified using thermal desorption techniques. EERC researchers performed 

numerous experiments to confirm or refute this hypothesis. The experimental design focused on 

the use of analytical spikes using mercuric chloride and elemental mercury. CCB samples, quartz 

sand, and quartz powder were all used as a base sample for these evaluations. Mercuric chloride 

was dissolved in ether and then added to the base samples. Elemental mercury was added in a 

gaseous form to CCB samples. The spiked samples were then desorbed using the same apparatus 

and protocol for the elevated-temperature vapor-phase mercury release experiments described 

above. 

4.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport 

4.5.3.1 Description of Initial Apparatus and Method 

 The first apparatus assembled to conduct microbiologically mediated vapor-phase mercury 

release used a 250-mL Erlenmeyer flask fitted with an impinger inlet/outlet tube, with the inlet 

center shortened to 6 cm below the standard taper. Cylinder gas was passed through several sets 

of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas 

distribution manifold that routed the gas through 0.25-mm GC capillary tubing to each of the 

individual flasks. A GC capillary length of approximately 60 cm, when pressurized to between 1 

and 2 psig through a gas distribution manifold, provided a convenient means of regulating gas 

flow to approximately 2 cm3

/min. The gas carried mercury vapor from the headspace of the 

flasks to a mercury vapor collection system at the outlet of the flasks, consisting of two traps. A 

Supelco CarbotrapTM (for collection of organomercury compounds) and a gold-coated quartz trap 

(for collection of elemental mercury) were used to collect mercury released in the vapor phase 

from the flasks. 

 The flasks were placed on a 16-flask wrist action shaker. The experimental matrix 

consisted of eight flasks under anaerobic conditions (using argon) and eight flasks under aerobic 

conditions (using breathing-quality air). In each set of eight flasks, two contained only buffer, 

three contained the CCB with buffer (starved), and three contained the CCB with buffer and 

glucose (fed). A 50-g aliquot of CCB was placed in the flasks, and ~100 mL of a phosphate 

buffer (with or without glucose, as appropriate) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bacterial culture added. The source of bacteria was a 

mixed bacterial innoculum from a brackish wetland. This setup is illustrated in Figure 4-9. 

4.5.3.2 Modifications of the Apparatus and Experimental Design 

 The apparatus as described underwent several iterations as difficulties were identified and 

solutions developed. The wrist-action shaker was abandoned, as it was inadequate to suspend the 

sample during the experiments. Instead of the wrist action shaker, samples were placed in 

Erlenmeyer flasks on a 9-place stir plate. This was operated for about 20 min every 3 h to 

maintain sample agitation over the duration of the experiment. Additionally, the sample size was 
21 

Figure 4-9. Early microbiologically mediated mercury vapor-phase collection apparatus utilizing 

a wrist action shaker to facilitate mixing.

reduced to 20 g and the buffer increased to 135–150 mL to provide adequate sample volume for 

additional trace element analyses. The buffer composition was also altered. It was found that 

phosphate and nitrate interfered with a derivitization step in the determination of organomercury 

compounds in the solid-phase microextraction (SPME) process using gas chromatographic 

separation followed by detection of the mercury compounds by AF. This technique is described 

in Section 4.5.3.6. The original buffer utilized nominal concentrations of phosphate and nitrate 

salts. The improved buffer used only 100 ppm of phosphate and substituted potassium glutamate 

as the nitrogen source. This simple change appeared to remove the interferences. Additionally, 

later experiments did not involve the use of starved control samples. In current experiments, all 

samples are fed with glucose. Table 4-1 summarizes the modifications and indicates the 

experimental difficulties that the modifications were employed to correct or improve. The final 

experimental apparatus used for the majority of the project microbiological experiments is 

illustrated in Figure 4-10. 

4.5.3.3 CCB Preparation Methods 

 Some CCBs, especially fly ash, can be alkaline in nature. CCB alkalinity can be attributed 

to the dissolution of alkaline metal oxides that react with water to generate net alkalinity. Watersoluble calcium content contributes most of a CCB’s net alkalinity. This trend can be seen in the 

classification of fly ashes; Class C fly ash is enriched in Ca and Mg and subsequently generates 

pH values considerably higher than Class F fly ash (e.g., pH >10). 
22 

Table 4-1. Microbiological Rerelease Apparatus Modifications 

Original Experiment or Apparatus 

 Component Difficulty or Unmet Need 

Modified Experiment or 

Apparatus Component 

Wrist Action Shaker, 

 Continuous Shaking 

Inadequate suspension of sample. Magnetic stir plate, 

 intermittent stirring. 

50–80-gram Sample Size + 

 ~100-mL Buffer 

Inadequate volume of liquid to 

 recover for leachate analysis. 

~20-gram sample + 135– 

 150 mL buffer. 

Phosphate Nitrate Buffer Solution Interference with the determination of 

 the organomercury compounds in 

 leachate. 

Lower concentration of 

 phosphate with potassium 

 glutamate as nitrogen 

 source. 

Glucose-Fed and Starved 

 Experiments 

Starved experiments did not promote 

 microbial growth so were deemed 

 unnecessary. 

All experiments fed with 

 glucose. 

Gold-Coated Quartz Trap 

 Followed by Carbotrap at Gas 

 Exit (only in Experiment 1) 

Organomercury was trapped on the 

 gold-coated quartz so 

 organomercury could not be 

 measured separately. 

Carbotrap was followed by 

 gold-coated quartz trap at 

 gas exit. 

Figure 4-10. Microbiologically mediated mercury vapor-phase collection apparatus utilizing a 

stir plate to facilitate mixing. 

 In order for a CCB, or any material, to support biological activity, it must be near-neutral 

pH. A pH range of 6.5 to 8.5 was used for optimal microbiological activity, requiring substantial 

neutralization of some CCBs. Prior to initiation of experiments, the buffer for that experiment 

was added to individual samples, pH of the ash–buffer mixture was measured, and an appropriate 

volume of acid was added over a period of time to achieve a neutral pH. 
23 

4.5.3.4 Microbiological Innoculum Growth Conditions and Media 

 Since the microbes that promote the release of mercury are ubiquitous, freshly collected 

sediment from a local brackish wetland was used as the innoculum. This innoculum contained a 

variety of microbes including both aerobic and anaerobic bacteria and, therefore, was identified 

as an appropriate innoculum. The source of the innoculum was the same for all experiments. 

 The innoculum was prepared by using 1 g of sediment taken approximately 2 mm from the 

surface of the sample so that is was more likely that a high concentration of anaerobic organisms 

would be present. This sample was added to 10 mL of 0.9% NaCl and vortexed. This suspension 

was then used to inoculate the CCB slurry samples. 

4.5.3.5 Experimental Incubation Conditions 

 Samples were allowed to incubate in sealed flasks at room temperature for 4 weeks. 

Experiments were all performed in triplicate. Table 4-2 provides information on the incubation 

conditions for microbiological rerelease experiments performed under this project. 

4.5.3.6 Mercury Analyses 

 The mercury collected in the traps designed to collect mercury released in the vapor phase 

was quantitated at the conclusion of each experiment. Hg analytical traps were analyzed as noted 

in 4.4.1.7 above. 

 The leachate was separated from the sample in order to determine the concentrations of 

mercury in solution. Total mercury concentrations of the leachate were determined using 

CVAFS or CVAAS. 

 In order to determine organomercury species of the mercury present in the leachates, 

SPME was used. SPME is a sample collection technique utilizing a fiber coated with 

polydimethylsiloxane. Samples containing organomercury compounds are first derivatized to 

increase the volatility of organomercury halides such as methylmercuric chloride. The 

derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and 

sodium tetraphenyl borate. Sodium tetraethyl borate was most commonly used. In the 

derivitization procedure, derivatizing agent, acetate buffer, an internal standard (usually propyl 

mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, 

the halide is replaced with the appropriate alkyl or aryl group, depending on which derivatizing 

agent is chosen. Five mL of the liquid plus an aliquot of ethylmercuric chloride as an internal 

standard was placed into a 15-mL septum-capped nonactinic vial containing a Teflon-coated stir 

bar. 500 μL of a pH 4.5 acetate buffer was added followed by 200 μL of a 1% solution of sodium 

tetrapropylborate. SPME sampling was accomplished using a 100-μm polydimethylsiloxanecoated fiber and sampler from Supelco (Bellefonte, Pennsylvania). An SPME fiber was inserted 

through the septum cap, and the sample was stirred using a Teflon-coated stir bar for 20 min. 

After this equilibration time, the SPME fiber was introduced into the heated inlet zone of a GC. 

Sample separation can be accomplished using a 0.53-mm capillary column 15 or 30 m in length. 
24 

Table 4-2. Microbiological Experimental Incubation Conditions

Experiment No. 

Number of 

Samples Run 

in Triplicate 

Apparatus 

Used Acid Addition Buffer 

Ash-to-Buffer 

Ratio 

1 1 Original 

apparatus 

None Phosphate/nitrate buffer 50 g to 94 mL An

 w st

2 1 Original 

apparatus 

None Phosphate/nitrate buffer 50 g to 100 mL An

 w st

3 1 Original 

apparatus 

Phosphoric acid  added to neutralize  solution pH to  allow microbial  growth 

Phosphate/nitrate buffer 80 g to 100 mL An

 w st

4 3 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth 

Phosphate/glutamic acid  buffer 

20 g to 150 mL An

 gl

5 3 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth for  fly ash samples 

Phosphate/glutamic acid  buffer 

20 g to 150 mL An

 gl ba FG

6 4 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth 

Phosphate/glutamic acid  buffer 

18 g to 135 mL An

 gl
25 

The exit end of the column was connected to a heated quartz tube (800°C), and makeup helium 

gas was added to increase the total flow to between 25 and 30 mL per minute. The gas was then 

routed to an AF detector for determination of the separated mercury compounds. 

4.5.3.7 Microbiological Analysis 

 Bacterial counts were performed upon completion of the experiments to determine if there 

were adequate active microbes present at the completion of the experiment to account for any 

mercury releases found. A 1-mL aliquot of solution was taken from each flask. Prior to 

processing, the ash sample was stored in a flask at 4°C. When processing, 100 μL was removed 

and added to 9.9 mL sodium pyrophosphate (PP) buffer (0.1% w/v) pH 7.0 with three glass 

beads in each test tube. This was vortexed for 30 s then serially diluted into PP buffer (up to 

1/1000 dilution). These dilutions were used to inoculate a 3-tube most probable number (MPN) 

assay with 1% peptone–tryptone–yeast extract–glucose (PTYG) buffer. Four mL of PTYG was 

placed in each 13 × 100-mm tube along with innoculum and incubated at room temperature. 

Tubes and plates (peptone–yeast extract–glucose [PYG] agar) inoculated with samples from the 

anaerobic ash suspension were incubated under anaerobic conditions (anaerobic hood), and 

aerobic ash suspension samples were exposed to atmospheric oxygen. At week intervals, they 

were scored based on turbidity. 

4.6 Field Investigations 

 The objective of this task was to develop information to facilitate an understanding of how 

laboratory results can be used effectively to determine potential releases of ATEs from CCBs in 

real-world management settings. Phase one of this task included a field sampling event at a 

lignite-based power plant disposal facility. Following assembly of the phase one results, project 

sponsors and researchers agreed that additional field measurements would not be expected to 

yield adequate data to allow the development of a method that directly correlated laboratory data 

with field data, so an alternate laboratory evaluation for measuring microbiologically mediated 

Hg releases was designed as phase two of the task. 

4.6.1 Field Task 1 

 Phase one of the field investigation was performed at CCB management facilities 

associated with a lignite-fired power plant. The field task consisted of three key activities: 

1) collection of near-surface solid samples and water samples where available, 2) mercury flux 

measurements taken at near-surface locations, and 3) collection of mercury samples from CCB 

and fill air at near-surface locations. The EERC contracted with the University of Nevada–Reno 

(UNR) to perform the mercury flux measurements. 

 The EERC methodology for determining CCB landfill air mercury levels was performed at 

several locations at the CCB management facility including a fly ash disposal site, a site where 

wet FGD material and mill rejects were codisposed, a reclaimed fly ash landfill site, near a 

disposal pond containing wet FGD material and bottom ash, and near a disposal pond containing 

wet FGD material stabilized with fly ash. The mercury-sampling sites are outlined in Table 4-3. 
26 

 Table 4-3. Mercury Measurement Site Descriptions 

Substrate Type Site Description 

Fly Ash Uncovered, fly ash landfill 

Vegetated Fly Ash with Soil 

Cover 

Closed, reclaimed (vegetated) fly ash landfill with 2-ft clay 

cap and 3-ft soil cover 

Wet FGD Material + Mill 

Rejects 

Uncovered disposal of material from ash Pond 91 during 

2003 

Wet FGD Material (wet 

disposal) 

Wet disposal in the middle of the pond (unstabilized) 

Bottom Ash/Mill Rejects + Wet 

FGD material (wet disposal) 

Wet disposal in the middle of the pond (unstabilized) 

surrounded by a bottom ash embankment 

Stabilized Wet FGD Material 

(with fly ash) 

Uncovered HDPE1

-lined facility (stabilized) 

Natural Grasslands (background 

soil) 

Natural grassland 

Agricultural land Agricultural land actively farmed 

1

 High-density polyethylene. 

CCB landfill air was drawn through gold-coated quartz traps and tubes containing Supelco 

CarbotrapTM. The combination of collection on these two types of analytical traps allowed 

assessment of inorganic mercury (gold trap) and organomercury species (Supelco CarbotrapTM). 

Traps were analyzed as noted in the laboratory methods section of this report (4.4.1.7). 

 Solid samples and water samples were obtained for laboratory testing. Solid composite 

samples were taken of the substrate on which the mercury air sampling was conducted. 

Composite samples are described in Table 4-3. Liquid samples were collected at disposal ponds 

where possible. A map showing sampling locations is shown in Figure 4-11. 

 In situ mercury flux was measured by UNR research staff using two field flux chambers 

linked to a total mercury analyzer (Tekran 2537A) systems. Mercury fluxes for the field chamber 

measurements were calculated using the Hg flux rate, outlet and inlet air Hg concentrations, 

airflow rate, and soil surface area covered by the chamber. Chamber blanks were also obtained. 

This method has been successfully applied before at other fly ash sites (Gustin and Ladwig, 

2004). Micrometeorological parameters were also measured during the same time frame as the 

flux measurements. These included air and substrate temperatures, relative humidity, and 

incident light. Several solid samples were collected at each field sampling location for 

determination of total mercury. For each material, fluxes were measured from at least three 

locations (Xin et al., 2006) 

4.6.2 Alternate Field Task 

 The phase two field investigation (alternate field task) was designed to evaluate the impact 

of interaction between soil and fly ash on mercury release from fly ash. The interaction of 

greatest interest was that caused by inherent microbiological organisms typically found in soils. 

The CCB–soil laboratory experimental apparatus was designed to evaluate microbiologically 
27 

Figure 4-11. Field sampling site map. 

mediated mercury release from CCB–soil mixtures, analogous to utilization management 

practices in the field. The experimental protocol was similar to the long-term ambienttemperature experiment and used a similar apparatus. A schematic of the apparatus is shown in 

Figure 4-12. Note that an inverted funnel was placed over the soil–ash bed to facilitate collection 

of released mercury. 

 A 20% addition of CCBs was combined with the soil and mixed thoroughly. The soil 

consisted of a mixture of topsoil, potting soil, and peat moss, which had moisture added to 

increase existing microbial activity. Approximately 200 grams of this mixture was placed in 

sample containers. Mercury-free air entered the sample container, swept over the sample, and 

exited through an inverted glass funnel. Organomercury compounds were captured on a 

collection trap containing Supelco CarbotrapTM, and elemental mercury was captured on goldcoated quartz. Six fly ash–soil mixtures, one FGD material–soil mixture, and soil alone were set 

up in duplicate. 

 After a period of mercury collection, the Supelco CarbotrapTM and gold-coated quartz 

analytical traps were analyzed for captured mercury as noted previously. All sample containers 

were subjected to a blanking process to account for elemental mercury present in the empty 

container and the scrubbed air entering the system. 

4.7 Data Reduction and Interpretation 

 The quality objectives of this effort support continued environmentally responsible 

management of CCBs and appropriate federal regulation of CCBs. The quality objective was to 
28 

Figure 4-12. CCB–soil mercury vapor release collection apparatus. 

select and/or modify experimental methods that would be most appropriate for the material 

types. 

 Because this was a laboratory project to evaluate mercury stability in CCBs, most of the 

analyses of the samples were done using standard EPA-approved laboratory methods. Other 

laboratory techniques that did not have specific EPA-approved methods were performed in 

accordance with standard EERC laboratory practice. 

5.0 RESULTS AND DISCUSSION 

5.1 Literature Search 

 The online database of literature gathered over the project duration, modeled after the 

EERC’s FIRST SEARCH database, is located on the Coal Ash Resource Center Web site at 

www.undeerc.org/carrc/mercury. A user name and password are required, which allows only 

project sponsors and researchers to access the database. The database can be quickly searched 

using the “Quick Search” tool or the “Advanced Search” tool; it can be searched for a specific 

title, author, source/publisher, or abstract text. Users may also browse all publications in 

alphabetical order by title. The majority of publications contain abstract text, and a method is 

provided to acquire the full text. In several instances, full text is provided free of charge by 

following the full text instructions. The database contained 526 documents. In addition to these 

documents being made available to project researchers and sponsors, many of these documents 
29 

were used in preparation of research status reports under a separate effort for the Canadian 

Electric Association, and those reports are included in Appendix C. 

 The literature assembled indicated the following: 

• Most work in the area of mercury stability/release from CCBs has been published after 

2004. 

• The rerelease mechanism that has the most data available is that of direct leaching. 

Direct leaching evaluations have been performed primarily on fly ash, with limited 

activities on FGD materials. Several groups, including the EERC’s reports from this 

project, reported low mobility of mercury from fly ash due to leaching. 

• The mechanisms of vapor-phase rerelease and microbiologically mediated leaching and 

vapor-phase rerelease were investigated since 2004 but the data reported in the literature 

were limited. 

• Field-generated data were consistent with laboratory data even though only limited field 

investigations were reported in the literature. 

5.2 Analytical Methods Selection 

 The methods selected for use in this project are listed and described in the experimental 

section. For the most part, methods used were standard methods. Both ASTM and EPA methods 

were used when available. Where required, exceptions to the use of standard methods were also 

described in the experimental section and in a report prepared earlier in the project to summarize 

the analytical and release methods selected. That report is included in Appendix D. 

 The leaching method selected, SGLP–LTL, was selected based on EERC experience and 

familiarity with a large number of leaching procedures used to characterize CCBs and the 

appropriate application of those tests. SGLP–LTL meets the criteria that EERC researchers have 

identified for leaching procedures to provide scientifically valid information. These criteria are 

as follows: 

• Reactivity or other properties of the material being leached that may influence the 

leaching profile. 

• The setting where the material is to be placed and the water that will most likely contact 

that material in that setting. 

• The leaching time required to allow adequate time for hydration reactions to occur in 

reactive materials, such as high-calcium coal fly ash. 

 The elevated-temperature vapor-phase release method, developed at the EERC in 1998 

(Pavlish, 1999) underwent minor modifications early in the project as described in the 

experimental section of this report, but has been shown to provide reproducible data. The 
30 

remaining technical challenge with the method as employed for this project is the limitations 

associated with the maximum achievable temperature to be applied to the CCB under 

investigation, and this cannot be addressed under this project. The method also has limitations 

for samples with high sulfur content because sulfur compounds are released as a gas on sample 

exposure to elevated temperatures and are an interference to the determination of mercury. 

 The ambient-temperature vapor-phase release method developed for this work also 

presents technical challenges, but these are related to the quantitation limitations for mercury. 

The extremely low levels of mercury released at ambient temperatures are frequently near the 

levels of detection for the analytical system being used. The physical nature of the CCB samples 

also results in variable data and the need to modify the method. As an example, using the 

apparatus to evaluate the potential for release of mercury from a wet FGD material required 

modification of the apparatus to shorten the gas inlet tube to above the level of the sample 

because gas could not be forced through the material when the inlet was near the bottom of the 

sample container. 

 The EERC method developed to evaluate the microbiologically mediated release of 

mercury underwent significant modifications during the project. For samples of low to moderate 

pH and low sulfur content, the apparatus noted in Figure 4-10 was appropriate and allowed 

collection and analysis of mercury released in the vapor phase and by leaching. For alkaline 

samples and those with high sulfur content, including FGD materials, the apparatus shown in 

Figure 4-12 was developed and used for determining the microbiologically mediated releases of 

mercury from CCBs by mixing the CCB sample with soil and introducing a low-mercury 

airstream. Analytical traps were used to capture organomercury and total mercury released as a 

vapor. This apparatus was used to complete the microbiological experiments, and because soil 

was used in the sample setup, these experiments also served to complete the work for the field 

task, which had been modified as noted in the experimental section. 

5.3 Sample Identification and Selection 

 Sample selection was initiated by identifying samples that would potentially be available 

through government, industry, and marketing contacts. CCBs were selected from systems with 

conventional emission control technologies and advanced emission control technologies. 

Samples included 1) currently produced fly ash from a variety of coal sources and system 

configurations; 2) wet and dry FGD materials, focusing on processes with a higher probability 

for future installation; and 3) CCBs from pilot-scale or experimental emission control 

technologies with a high potential to be implemented under existing or expected regulations. For 

activities related to experimental protocol and analytical methods development, high-mercury fly 

ash samples were used in order to allow measurements of mercury above the lower level of 

quantitation (LLQ). These samples were selected from systems producing fly ash with higherthan-average carbon content or, in some cases, those from fabric filter collection systems. The 

best choices for samples were those collected from full-scale combustion and FGD systems; 

however, these were not always available, especially for mercury control technologies and early 

in the project before large-scale DOE mercury emission control tests were initiated. Throughout 

the project, samples from systems with advanced emission controls were collected from system 

technologies in the research, development, and demonstration phases under DOE and other 
31 

programs focused on emission control. Some samples were collected from bench- or pilot-scale 

studies because those samples were the only ones available at the time. 

5.3.1 Sample Prioritization 

 A sample prioritization was performed as part of the project kickoff meeting, and the 

results of that effort (included in Appendix E) provided a target list of sample types to include in 

the project sample set. The highest-priority samples were identified to be those generated using 

the following: 

• Bituminous, subbituminous, and lignite in pulverized coal (pc)-fired units and fuel oil 

• Fabric filter or ESP cold side 

• No FGD system or wet calcium-based FGD process or SDA. 

• No ammonia-based system or ammonia injection or selective catalytic reduction (SCR). 

 High priority was also given to samples that could be collected from full-, pilot-, or benchscale systems for mercury emission control as follows: 

• Carbon injection 

• Noncarbon sorbent injection 

• Modified FGD 

• Fine particulate control 

• Fly ash from carbon removal technologies 

 It was also noted that, where possible, samples representing a “baseline” and “test” sample 

pair should be obtained. The project sample set included primarily samples identified as high 

priority. Samples generated from pc-fired systems using 100% bituminous, subbituminous, and 

lignite constituted the majority of the samples collected for the effort. The majority of fly ash 

samples that were collected from demonstrations of mercury emission control systems had AC 

used as a sorbent. Only one paired set of fly ash samples was obtained from a fine particulate 

control system being tested for mercury capture. While no noncarbon-based sorbent samples 

were collected, one sample where a chemical “enhancing agent” was added was obtained and 

evaluated. 

 A summary of samples finally selected for use in this project is included in Tables 5-1–5-3. 

A complete listing of samples and the identification information are included in Appendix F. 

Based on the sample quantity, quality, and relevance to the project, mercury and ATE release 

experiments were performed using these samples; however, not all samples were subjected to all 

types of release experiments, and some samples collected or submitted for the project were not 

included in the final sample selection. Reasons for excluding samples from the selected sample 

set were the following: 

• Insufficient sample to perform characterization analyses and release experiments 

• Insufficient sample identification information 

• Sample not representative of typical coal-based systems 

• Sample poorly taken or stored prior to receipt so integrity was in question
32 

 Table 5-1. Summary of Fly Ash Samples and Fundamental Characterization Data 

Coal Type 

No. of 

Fly Ash 

Samples 

No. of Fly Ash 

Samples from 

Hg Control 

24-hour pH 

Range 

LOI 

Range, % 

Total Hg 

Concentration 

Range, μg/g 

Eastern 

 Bituminous 

17 5.52–12.44 0.47–6.27 <0.01–0.685 

 

6 with AC (postprimary PCD) 3.99–9.20 12.6–24.4 0.742–120 

South American 

 Bituminous 

2 9.13 12.7–21.2 0.151–0.607 

 2 with AC (preprimary PCD) NT1

 NT NT 

Western 

 Bituminous 

2 10.38–12.65 1.42–2.56 0.144–0.521 

Subbituminous 3 12.27–12.56 0.32–1.08 0.261–1.22 

 4 with AC (preprimary PCD) 10.95–11.90 2.28–4.14 1.09–5.81 

Lignite 13 10.50–12.74 0.22–7.48 <0.01–0.878 

 

4 with AC (preprimary PCD) 11.86–12.61 0.96–4.21 0.225–2.22 

 

3 with EA2

 + AC 

(pre-primary 

PCD) 

12.29–12.77 1.04–2.49 0.287–0.640 

 1 with EA 11.77 1.70 0.717 

 

10 with AC 

(post-primary 

PCD) 

10.52–12.00 0.59–13.2 0.147–64.5 

1

 Not tested. 

2

 Enhancing agent. 

 As noted, the sponsor sample prioritization process indicated that an effort should be made 

to collect “paired” samples from full-scale demonstrations of mercury emission control 

technologies. These sample pairs included a baseline sample (collected when the system was 

running with standard conditions and no mercury emission control was imposed) and a test 

sample (collected during a mercury emission test). These samples were collected from the same 

location at a single site; however, the sample collection point and protocol varied between sites 

because of differences in the type of emission control and availability of sampling locations. 

Table 5-4 lists the paired sample sets, a brief description of the mercury control technology used, 

and fundamental characteristics of the samples. A total of eight paired sample sets were collected 

and evaluated in various release experiments in the project. 
33 

 Table 5-2. Summary of FGD–SDA Samples and Fundamental Characterization Data 

Coal Type 

No. of 

FGD–SDA 

Samples 

No. of FGD–

SDA Samples 

from Hg 

Control 

24-hour 

pH 

Range 

LOI 

Range, % 

Total Hg 

Concentration 

Range, μg/g 

Lignite 3 12.50 0.95–12.5 <0.01–2.55 

 

1 with EA + 

ACI (pre-SDA) 12.54 1.12 0.332 

Subbituminous 1 12.22 2.07 0.105 

 Table 5-3. Summary of Eastern Bituminous Wet FGD Material Samples and 

 Fundamental Characterization Data 

SO2 Control 

No. of FGD 

Samples by 

Sample Type 

24-hour pH 

Range 

LOI 

Range, % 

Total Hg 

Concentration 

Range, μg/g 

Wet Mg- 

 Enhanced Lime 

2 FGD gypsum 7.75–7.88 1.22–1.92 0.032–0.044 

Wet Limestone – 

 Forced Oxidation 

3 FGD gypsum 7.72–7.95 1.60–2.26 0.043–0.103 

Wet Limestone – 

 Nonoxidized 

3 FGD filtercake 7.70–7.88 4.20–6.19 0.162–0.305 

Wet Limestone – 

 Nonoxidized 

3 Fixated FGD 10.50–12.43 3.11–4.17 0.136–0.249 

5.3.2 Sample Handling 

 Fly ash as produced from full-scale coal-based systems is generally considered to be 

homogeneous on the macroscale and heterogeneous on the microscale. This means that a sample 

of fly ash collected using appropriate compositing techniques will usually provide a high-quality, 

representative sample on which the bulk characteristics can be determined with good accuracy. 

On the microscale, however, the individual particles will not necessarily reflect the bulk 

characteristics of the material because of the manner in which the individual particles are formed 

during the combustion process. FGD materials are generally considered homogeneous on both 

the macro- and microscale.

 For this project, the fly ash samples frequently were visually nonhomogeneous because of 

the presence of AC. Research staff frequently noted the presence of carbon as discreet particles 

within the fly ash sample matrix and also noted that the particle sizes of carbon present could be 

easily distinguished visually. On agitation of the glass sample containers, the segregation of fly 

ash and carbon was also frequently noted. This obvious nonhomogeneity required increased care 

in obtaining analytical subsets of the bulk samples. Several approaches were used to ensure 

representative samples were used. Bulk samples were gently agitated, and the sample was 
34 

Table 5-4. Paired Samples and Fundamental Characterization Data 

ID Nos. Sample Type 24-hour pH LOI, % Hg, μg/g 

02-070 Fly ash 8.50 5.87 0.194 

02-069 Fly ash + AC (post-primary PCD) 8.43 12.60 0.742 

02-072 Fly ash 8.83 5.29 0.163 

02-071 Fly ash + AC (post-primary PCD) 8.63 17.22 0.975 

03-061 Fly ash 12.56 1.04 0.578 

03-060 Fly ash + AC (pre-primary PCD) 11.90 2.38 1.86 

04-035 Fly ash 12.74 2.46 0.159 

04-036 Fly ash + EA + AC (pre-primary 

PCD) 

12.77 2.33 0.287 

05-001 Fly ash 12.51 0.90 <0.01 

05-003 Fly ash + EA + ACI (pre-SDA) 12.29 1.04 0.565 

05-005 Fly ash 11.57 1.29 0.431 

05-017 Fly ash + EA 11.77 1.70 0.717 

05-038 Fly ash 11.73 0.22 0.104 

05-013 Fly ash + AC (post-primary PCD) 11.33 13.2 39.0 

05-023 Fly ash + AC (pre-primary PCD) 12.00 3.84 12.7 

05-024 Fly ash + AC (post-primary PCD) 11.41 9.45 35.9 

05-025 Fly ash + AC (pre-primary PCD) 11.99 3.19 12.6 

05-040 Fly ash + AC (post-primary PCD) 11.36 9.68 44.5 

06-001 Fly ash + AC (post-primary PCD) 11.37 11.6 64.5 

05-002 Fly ash + FGD–SDA 12.50 0.95 <0.01 

05-004 Fly ash + FGD–SDA + EA + AC (preSDA) 12.54 1.12 0.332 

observed to get the carbon distributed representatively through the bulk sample container. For the 

total mercury and ATE analyses, duplicate samples were used, and in some cases where the 

carbon content was especially problematic or the mercury content very low or very high, up to 

eight replicates were run. For the elevated-temperature release experiments, where only very 

small samples could be introduced into the experimental apparatus, samples with large carbon 

particles present were ground to produce a more homogeneous sample. 

 FGD material samples with water standing were dewatered for use in release experiments. 

This was done by pouring of the majority of water and filtering through a Bhchner funnel or 

pressing the solid, depending on the experiment the sample was to be used in. 

5.3.3 Sample Descriptions 

 The samples selected for evaluation in this project were obtained from samples collected 

from bench-, pilot-, and full-scale combustion systems and from demonstration of multiple 

mercury emission control systems and types. In order to adequately describe the samples for the 

purpose of the discussion of the data and to draw conclusions while maintaining confidentiality 

of sample identity, the following sample descriptors were developed and are used throughout this 

report. 
35 

Fly ash – Fly ash sample that was generated under operating conditions that were not influenced 

by a mercury control technology. These samples may be generated in systems with NOx, SOx, or 

other emission controls, and the specific system type is noted in Appendix F. 

Fly ash + AC (pre-primary PCD) – Fly ash that has AC present as a result of ACI for mercury 

emission control. The AC was injected before the primary PCD. 

Fly ash + EA (EA on coal) + AC (pre-primary PCD) – Fly ash that has AC present as a result 

of ACI for mercury emission control and has another chemical that was also introduced to 

enhance mercury uptake by the fly ash + AC. The EA was added to the coal. The AC was 

injected before the primary PCD. 

Fly ash + EA (EA on coal) – Fly ash that has a chemical that was introduced to enhance 

mercury uptake by the fly ash or to change the oxidation state of the mercury present to enhance 

mercury uptake in an existing FGD system. The EA was added to the coal. 

Fly ash + AC (post-primary PCD) – Fly ash that has AC present as a result of ACI for mercury 

emission control. The AC was injected after the primary PCD and the fly ash + AC were 

collected in a secondary PCD. This type of sample would include samples produced in a 

TOXECONTM system. In this type of system, a portion of the fly ash would have already been 

removed by the primary PCD, so only a fraction of the total fly ash generated would be mixed 

with AC. 

FGD–SDA – An FGD material from a SDA configuration. FGD–SDA uses a calcium-based 

sorbent (lime or hydrated lime) to remove SO2 from the flue gas. Calcium sulfite and calcium 

sulfate are the primary products of the reaction of the sorbent and the SO2. In the United States 

(and in all project samples), fly ash is usually incorporated into the SDA system, so the solid byproduct contains a mixture of the calcium sulfite and sulfate and fly ash. 

FGD–SDA + EA (EA on coal) + AC (pre-primary PCD) – An FGD material from a SDA 

configuration where EA was added to the coal and AC was injected ahead of the SDA. 

Wet FGD material – Any material producted from wet flue gas scrubbing utilizing a calciumbased sorbent. 

FGD gypsum – FGD material from a wet system employing forced oxidation, producing 

gypsum (ca SO4· 2H2O). The sorbent may be limestone or magnesium-enhanced lime, also called 

dolomitic lime. 

Wet FGD slurry – Material produced in a wet FGD system that uses inhibited oxidation or 

natural oxidation. It is typically a wet, thixotropic material containing both calcium sulfite and 

calcium sulfate. It may also be referred to as “nonoxidized” FGD material. 

FGD filtercake – The resulting material after filtration of wet FGD slurry. 
36 

Fixated wet FGD material – Wet FGD material that has a stabilizing agent (typically fly ash) 

added to it to facilitate handling. 

5.4 Chemical and Physical Characterization 

 The bulk chemical and physical characterization task focused on determining trace element 

composition, moisture content, LOI, pH, and carbon forms. Total major and minor constituents 

were also determined on a limited number of samples. 

5.4.1 Total Mercury and ATEs 

 In order to adequately determine the release of mercury and other ATEs from fly ash and 

FGD materials, the total concentrations of these elements needed to be determined. The total 

trace element results for all samples evaluated are included in Appendix G. The ranges for all 

samples (fly ash with and without mercury control and all FGD materials) evaluated are as 

follows: 

• <1–492 μg/g arsenic 

• <1–8.59 μg/g cadmium 

• 2.90–160 μg/g chromium 

• <3–272 μg/g lead 

• <0.01–120 μg/g mercury 

• <1–277 μg/g nickel 

• <2–457 μg/g selenium 

 A more detailed summary of the ranges of total trace elemental concentrations in the fly 

ash, FGD–SDA samples, and wet FGD material samples selected for this project are shown in 

Tables 5-5, 5-6, and 5-7, respectively.

Table 5-5. Range of Total Trace Elements in Fly Ash Samples, μg/g

Element Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + 

EA 

Fly Ash + 

AC (postprimary 

PCD) 

As 5.90–492 19.4–73.9 26.8–46.3 NTa 35.3–444 

Cd <1–8.59 <1–1.97 <1–0.942 NT <1–3.38 

Cr 43.4–160 39.1–111 44.8–49.1 NT 35.5–115 

Pb 17.4–272 30.3–87.1 18.3–25.9 NT 49.0–85.3 

Hg <0.01–1.22 0.225–12.7 0.287–0.640 0.717 0.147–120 

Ni 17.2–277 18.6–67.6 23.1–41.5 NT 15.4–94.5 

Se 3.97–44.7 13.4–69.4 9.86–18.3 NT 19.6–457 

a

 Not tested. 
37 

 Table 5-6. Range of Total Trace Elements in FGD–SDA Samples, μg/g 

Element FGD–SDA FGD–SDA + EA + AC (pre-primary PCD) 

As 14.7–22.6 21.8 

Cd <1 <1 

Cr 26.3–42.8 37.3 

Pb 18.6–37.0 20.9 

Hg <0.01–2.55 0.332 

Ni 12.9–29.7 25.3 

Se 9.15–9.92 9.79 

 Table 5-7. Range of Total Trace Elements in Wet FGD Material Samples, μg/g 

Element FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD Material 

As <1–1.65 <1 <1 53.4–53.8 

Cd <1–1.89 <1 <1 1.08–1.24 

Cr 2.90–4.13 6.61 10.2–10.4 51.6–53.6 

Pb <3 <3 <3–4.40 80.3–86.7 

Hg 0.032–0.103 <0.1–0.196 0.162–0.305 0.136–0.249 

Ni <1–6.83 2.87 3.50–3.98 87.2–98.7 

Se <2–2.68 3.01 <2–2.64 3.71–4.46 

 For all elements except mercury and selenium, the fly ash samples from mercury control 

tests were within the ranges of fly ash samples without mercury control (Table 5-5). The 

concentrations of arsenic, cadmium, chromium, lead, and nickel measured in fly ash (without 

mercury control) selected for this project are also consistent with the concentrations of these 

elements measured in fly ash samples from previous EERC projects (Hassett and Heebink, 2002; 

Pflughoeft-Hassett et al., 2004, 1996). 

 Total mercury concentrations in the fly ash-based samples ranged as follows: 

• Fly ash (without mercury control) – <0.01–0.878 μg/g 

• Fly ash + AC (pre-primary PCD collection) – 0.225–12.7 μg/g 

• Fly ash + AC (post-primary PCD collection) – 0.147–120 μg/g 

 In all cases where ACI was used, the total mercury concentration range was higher than 

that noted for fly ash samples, providing an indication of increased mercury capture on the fly 

ash + AC samples. The highest individual mercury concentrations were noted for the fly ash + 

AC (post-primary PCD) category of fly ash samples. 

 Total selenium concentrations in the fly ash-based samples ranged as follows: 

• Fly ash (without mercury control) – 3.97–44.7 μg/g

• Fly ash + AC (pre-primary PCD collection) – 9.86–69.4 μg/g

• Fly ash + AC (post-primary PCD collection) – 19.6–457 μg/g 
38 

 Similar to the mercury data, the total selenium concentration range was higher for the fly 

ash + AC samples than the fly ash. Again, the highest individual selenium concentrations were 

noted for the fly ash + AC (post-primary PCD) category of fly ash samples. 

 Total concentrations of ATEs were determined in the FGD–SDA samples using the same 

analytical techniques as those used for the fly ash samples. Only a limited number of FGD–SDA 

samples were obtained for use in this project. The data in Table 5-6 represent two samples of 

FGD–SDA and one sample of FGD–SDA + EA + AC. The FGD–SDA + EA + AC had total 

trace elemental concentrations that fell within the range noted for the FGD–SDA samples 

evaluated. 

 The total mercury concentration in FGD material samples was determined by DMA or 

EPA Method 7471. Total concentrations of ATEs were determined in the FGD material samples 

using the same analytical techniques as those used for the fly ash samples. A limited number of 

FGD materials from wet systems were collected for evaluation in this project. None of the wet 

FGD materials were collected from systems with mercury emission controls in use. Total 

mercury and ATE content ranges for each wet FGD material type are noted in Table 5-7. The 

ATE concentrations are generally similar for the wet FGD filtercake, slurry, and gypsum; 

however, several of the ATE concentrations are elevated in the fixated wet FGD material, most 

notably the arsenic, chromium, lead, and nickel. It was hypothesized that the fly ash added to the 

wet FGD material as a stabilizer resulted in these elevated ATE concentrations. No associated fly 

ash sample was available to confirm or refute this hypothesis. 

 One FGD gypsum sample set was collected from a single plant with an SCR. One sample 

was collected when the SCR was on, and the second sample was collected when the SCR was 

off. However, these samples were not considered “paired” as the collection dates were 3 months 

apart, and it could not be ascertained if the coal source and other operating conditions were 

consistent between sample dates. The information for these samples is noted in Table 5-8. 

 Liquid from FGD samples was also analyzed for total trace elemental concentrations. 

These included FGD gypsum filtrate and lab-dewatered FGD liquor samples from FGD 

filtercake and FGD slurry. The ranges of total trace elemental concentrations are given in 

Table 5-9. All results are in Appendix H. 

 Table 5-8. Total Trace Elements in FGD Gypsum Samples 

 Comparing SCR On and SCR Off, μg/g

Element FGD Gypsum SCR On FGD Gypsum SCR Off 

As 1.65 <2 

Cd <1 <1 

Cr 3.39 3.95 

Pb <3 <3 

Hg 0.043 0.103 

Ni 6.83 6.81 

Se 2.56 2.68 
39 

 Table 5-9. Range of Total Trace Elements in FGD Liquor Samples, μg/L 

Element 

FGD Gypsum 

Filtrate 

Wet FGD Slurry 

Liquor 

Wet FGD 

Filtercake Liquor 

As 82.8 114 33.1–121 

Cd 4.79 0.790 2.09–4.34 

Cr 9.90 10.1 2.90–5.70 

Pb <2 <2 <2 

Hg <0.01 <0.15 <0.15 

Ni 338 258 88.8–333 

Se 684 1140 154–759 

pH 5.20 6.75 5.92–7.56 

 The total ATE concentrations were determined in these liquid samples in order to better 

understand the distribution of ATEs in FGD systems. Mercury was undetected in all FGD liquid 

samples as expected based on previous work (Hassett and Moe, 1997). Arsenic, nickel, and 

selenium were present in the liquid samples in relatively high concentrations. Since no mercury 

emission controls were in use while these samples were collected, it was not possible to 

determine if the ATE concentrations for FGD liquids will be impacted by mercury emission 

controls. 

5.4.1.1 Paired Samples 

 Several sets of “paired” fly ash samples and one set of FGD–SDA samples were collected 

and evaluated in this effort; the sample pairs and total mercury content are presented in 

Table 5-4. Total ATE content is noted for these paired fly ash samples in Table 5-10. 

5.4.1.2 Total Mercury and ATE Discussion 

 Fly ash selected for this project generally contained low concentrations of mercury (see 

Table 5-5), and total mercury concentrations were consistent with those reported elsewhere 

(Energy & Environmental Research Center, 2004; Energy & Environmental Research Center, 

2005; Sanchez et al., 2006). Total mercury content of fly ash + AC, regardless of ACI point, had 

higher ranges of mercury. Paired fly ash samples (Tables 5-4 and 5-10) clearly indicated that 

injection of AC does capture mercury, which results in elevated total mercury contents in the fly 

ash + AC samples as compared to the baseline fly ash samples. Other ATEs measured in all fly 

ash samples were generally present at similar concentrations regardless of whether the samples 

were collected with or without mercury emission controls in place. 

 For all FGD–SDA samples, the total concentrations of individual ATEs, including 

mercury, were similar for those with and without mercury emission controls in place. 

 The wet FGD material samples generally had lower total ATE concentrations than the fly 

ash and FGD–SDA samples, with the exception of the fixated wet FGD material. The 

concentrations of most ATEs were higher in those samples than the other wet FGD materials, 

likely because of added fly ash that was used for the fixation process. 
40 

Table 5-10. Paired Samples and Total ATE Content, μg/g 

ID Nos. Sample Type As Cd Cr Pb Hg Ni Se 

03-061 Fly ash 43.5 1.72 67.6 59.5 0.578 93.9 44.5 

03-060 Fly ash + AC (pre-primary 

PCD) 

19.4 1.87 76.7 82.2 1.86 67.6 34.2 

04-035 Fly ash 36.0 <1 55.4 21.9 0.159 17.2 9.78

04-036 Fly ash + EA + AC (preprimary PCD) 44.9 <1 48.8 18.7 0.287 23.5 10.4 

05-001 Fly ash 24.4 <1 45.1 17.4 <0.01 30.3 8.84

05-003 Fly ash + EA + AC (preSDA) 28.6 <1 45.5 21.2 0.565 25.7 11.5 

05-038 Fly ash 43.4 <1 43.4 90.1 0.104 21.1 23.4 

05-013 Fly ash + AC (post-primary 

PCD) 

38.6 <1 36.5 73.2 39.0 15.4 60.3 

05-023 Fly ash + AC (post-primary 

PCD: high fly ash) 

48.3 <1 42.6 87.1 12.7 18.6 22.5 

05-024 Fly ash + AC (post-primary 

PCD) 

42.5 <1 35.5 82.2 35.9 17.6 87.3 

05-025 Fly ash + AC (post-primary 

PCD: high fly ash) 

46.8 <1 39.1 84.7 12.6 20.4 30.1 

05-040 Fly ash + AC (post-primary 

PCD) 

38.4 <1 42.2 74.5 44.5 22.0 42.2 

06-001 Fly ash + AC (post-primary 

PCD) 

35.5 <1 39.8 72.0 64.5 20.6 38.9 

05-002 Fly ash + FGD–SDA 22.6 <1 42.8 18.6 <0.01 29.7 9.15

05-004 Fly ash + FGD–SDA + EA 

+ AC (pre-SDA) 

21.8 <1 37.3 20.9 0.332 25.3 9.79

 Review of the total ATE concentrations for the paired samples indicated that most ATE 

concentrations remained consistent between paired samples. Mercury was the only ATE that was 

consistently elevated in the test samples as compared to the baseline sample. A significant 

increase was noted in the total selenium concentration in fly ash + AC (post-primary PCD) over 

the baseline and fly ash + AC (pre-primary PCD) in one sample set. 

5.4.2 Total Bulk Chemical Composition 

 A limited number of samples were analyzed for total bulk chemical composition early in 

the project. The major and minor elements determined were silicon, aluminum, iron, calcium, 

magnesium, sodium, potassium, barium, manganese, titanium, phosphorus, strontium, and sulfur. 

The results of these analyses, reported as oxides as is convention with fly ash, are included in 

Appendix I. The data are summarized in Table 5-11, which also includes the ASTM C618 

specification for fly ash for use as a mineral admixture in concrete. 
41 

Table 5-11. Summary of Total Bulk Chemical Composition Compared to ASTM C618 

Specifications, % 

Parameter Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) FGD–SDA 

FGD 

Gypsum 

ASTM C618 

Class F Fly Ash 

Specifications 

ASTM C618 

Class C Fly Ash 

Specifications 

SiO2 + 

 Al2O3 + 

 Fe2O3

46.76–

92.25 

53.57–63.29 52.02 0.47 70 min. 50 min. 

SO3 0.06–

4.73 

1.43–5.89 13.60 51.14 5.0 max. 5.0 max. 

Moisture 

 Content 

0.01–

0.14 

0.05–0.23 1.01 17.37 3.0 max. 3.0 max. 

LOI 0.32–

4.25 

0.91–4.22 1.49 12.68 6.0 max. 6.0 max. 

 The sample set included five samples of bituminous fly ash, one sample of lignite fly ash, 

four samples of lignite fly ash + AC (pre-primary PCD), one subbituminous fly ash, and one 

subbituminous fly ash +AC (pre-primary PCD). The sample set also included one sample of 

FGD gypsum and one sample of FGD–SDA. Initially, it was proposed that these analyses would 

be valuable in data interpretation because they would provide information on the potential 

utilization options (mineral admixture for concrete, raw feed for cement kiln, cementitious 

applications, etc.) for the samples collected. The fly ash data shown in Table 5-11 indicated that 

the limited samples evaluated were typical of samples used as mineral admixtures for concrete, 

and even the samples with added AC met the specification for LOI in ASTM C618. It was 

determined that the LOI and chemistry of fly ash samples were not adequate to provide an 

indication of utilization performance, so this task was not providing the type of information 

anticipated. Further, it became apparent that many of the samples selected for release 

experiments in this project were not collected from locations typical of “as managed” samples 

that are usually evaluated for utilization potential. A decision was made with agreement from 

project sponsors to discontinue this subtask for those reasons. 

5.4.3 LOI and Moisture Content 

 The moisture content and LOI of solid CCBs were determined. Ranges of moisture content 

and LOI are presented in Tables 5-12 through 5-14. Moisture content and LOI results for all 

samples evaluated are included in Appendix J. As noted in Table 5-12, fly ash from mercury 

control technology testing had LOI values ranging from 0.59% to 24.4%. Fly ash without 

mercury control had LOI ranging from 0.22% to 21.2%. 

Table 5-12. Range of Moisture Content and LOI in Fly Ash Samples, % 

Parameter Fly Ash 

Fly Ash + AC (preprimary PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

Moisture 

Content 

0.02–1.00 0.00–1.07 0.05–0.85 0.05 0.10–5.56 

LOI 0.22–21.2 0.96–4.21 1.04–2.49 1.70 0.59–24.4 
42 

 Table 5-13. Range of Moisture Content and LOI in FGD–SDA Samples, % 

Parameter FGD–SDA 

FGD–SDA + EA + AC (preprimary PCD) 

Moisture Content 1.08–3.00 0.75 

LOI 0.95–12.5 1.12 

 Table 5-14. Range of Moisture Content and LOI in FGD 

 Material Solid Samples, % 

FGD Material Type Moisture Content LOI 

FGD Gypsum 21.6–26.7 1.22–2.26 

Wet FGD Slurry 56.8–65.7 4.37–6.38 

Wet FGD Filtercake 28.6–43.3 4.20–6.19 

Fixated Wet FGD 26.6–31.9 3.11–4.17 

 Moisture content and LOI for the paired fly ash and FGD–SDA samples selected for this 

project are shown in Table 5-15. LOI increased for all but one sample pair with the injection of 

AC. The largest increases in moisture content and LOI from the fly ash to the paired samples 

were noted in the fly ash + ACI (post-primary PCD) samples. The fly ash + ACI (post-primary 

PCD: high ash) samples in the largest paired sample set showed increased LOI values over the 

fly ash but were minimal compared to the other fly ash + ACI (post-primary PCD) samples 

within the sample set. The fly ash and FGD–SDA samples containing an enhancing agent on the 

coal in the mercury control technology testing generally showed the least change in moisture 

content and LOI. 

 Moisture content and LOI data for FGD–SDA samples selected for this project are noted in 

Table 5-13. For FGD–SDA samples, the LOI is likely dependent on the LOI of the fly ash that is 

incorporated into the FGD–SDA final by-product material. Most frequently, fly ash incorporated 

into FGD–SDA material is alkaline and provides some sorptive capacity for SO2 capture. It is 

also generally true that alkaline fly ash tends to have lower LOI than nonalkaline fly ash; 

however, as noted in the data in Table 5-13, a relatively high LOI value of 12.5% was measured 

in one FGD–SDA sample. Since no paired fly ash sample was available for testing, it is not 

known if this high LOI value is due to carbon present in the incorporated fly ash or is due to 

dehydration of hydrated phases present in FGD–SDA. FGD–SDA usually comprises relatively 

high percentages of calcium sulfite hemihydrate (CaSO3·1⁄2H2O, or hannebachite), which will 

lose water of hydration as well as SO2 at temperatures above 600°C. Since LOI determinations 

are carried out at 750°C, the values reported will be indicative of these losses as well as any 

carbon that may be in the sample. 

 Table 5-14 shows the data on moisture content and LOI for a variety of wet FGD materials 

selected for use in this project. The moisture content values reflect the water typically present in 

wet FGD materials. With the exception of FGD gypsum, the types of wet FGD materials noted in 

Table 5-14 comprise calcium sulfite and sulfate phases and, prior to filtering or fixation, are a 

thixotropic material with high water content and problematic handling properties. Even after 
43 

 Table 5-15. Paired Samples Moisture Content and LOI, % 

ID Nos. Sample Type Moisture Content LOI 

02-070 Fly ash 0.20 5.87 

02-069 Fly ash + AC (post-primary PCD) 0.78 12.6 

02-072 Fly ash 0.17 5.29 

02-071 Fly ash + AC (post-primary PCD) 1.18 17.2 

03-061 Fly ash 0.17 1.04 

03-060 Fly ash + AC (pre-primary PCD) 0.17 2.38 

04-035 Fly ash 0.14 2.46 

04-036 Fly ash + EA + AC (pre-primary 

PCD) 

0.06 2.33 

05-001 Fly ash 1.00 0.90 

05-003 Fly ash + EA + AC (pre-SDA) 0.85 1.04 

05-005 Fly ash 0.02 1.29 

05-017 Fly ash + EA 0.05 1.70 

05-038 Fly ash 0.04 0.22 

05-013 Fly ash + AC (post-primary PCD) 0.29 13.2 

05-023 Fly ash + AC (post-primary PCD: 

high ash) 

0.13 3.84 

05-024 Fly ash + AC (post-primary PCD) 0.23 9.45 

05-025 Fly ash + AC (post-primary PCD: 

high ash) 

0.07 3.19 

05-040 Fly ash + AC (post-primary PCD) 0.10 9.68 

06-001 Fly ash + AC (post-primary PCD) 0.39 11.6 

05-002 FGD–SDA 1.08 0.95 

05-004 FGD–SDA + EA + AC (pre-SDA) 0.75 1.12 

filtering or fixation, a significant level of moisture is maintained. The LOI is likely a result of 

loss of water of hydration or, in the case of the fixated FGD material, unburned carbon in the fly 

ash used as the fixation agent may contribute to the LOI. 

 FGD gypsum (calcium sulfate·2H2O), generally 95+% pure, exhibits lower moisture 

content because it is more readily separated from the water phase because of its crystalline form. 

The LOI for FGD gypsum is likely due to loss of water. 

5.4.3.1 pH 

 The pH of all samples of sufficient quantity was determined in distilled water with a 10–

15-minute equilibration time. Previous experience with fly ash and pH measurement raised 

questions about the most appropriate method to determine pH of CCBs. Since the pH of a 

material can influence the leaching profile and may impact the performance in certain utilization 

scenarios, including bulk placement in engineered fills, it is important to determine the pH as 

accurately as possible, even though the pH may change with time. It was decided to perform 

additional pH measurements including 24-hour (distilled water) pH and 10–15-minute pH using 
44 

1 M KCl (potassium chloride). All pH data collected on project samples are included in 

Appendix K. 

 Table 5-16 separates the pH values for all fly ash samples by coal type and pH test. Eastern 

bituminous fly ash samples exhibited a wide range of pH values in all tests. This range was 

greater in the fly ash samples without AC than with AC. The South American and western 

bituminous fly ash sample pH ranges were narrower and were closer to those of subbituminous 

and lignite fly ash samples than eastern bituminous fly ash samples. All fly ash + ACI (preprimary PCD) pH values, for the South American bituminous, subbituminous, and lignite 

samples in the project, were similar. The pH of all types of lignite fly ash samples were similar; 

however, the fly ash + AC (post-primary PCD) samples had pH values below 10 reported. The 

high-ash samples in the lignite fly ash + AC (post-primary PCD) exhibited the highest 24-hour 

pH values in that sample set. Overall, the difference between the 10–15-min and 24-hour pH 

tests is not significant but can be seen on a per-sample basis. 

 Some samples exhibited a near-neutral 10–15-minute pH, but after 24 hours of stirring, the 

pH increased to an alkaline value. During this equilibration time, the samples were stirred at 

350 rpm. As stated above, numerous samples exhibited pH values that changed substantially 

after 24 hours. Table 5-17 shows the sample information for these samples and the associated 

LOI. 

Table 5-16. Range of pH in Fly Ash Samples 

Coal Type pH Test Fly Ash 

Fly Ash + 

AC (preprimary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) 

Fly Ash + 

EA 

Fly Ash + 

AC (postprimary 

PCD) 

Eastern 

 Bituminous 

10–15-min 3.76–12.56 NA NA NA 3.47–9.59 

 24-hour 5.52–12.44 NA NA NA 3.99–9.20 

 1 M KCl 4.42–12.72 NA NA NA 3.51–9.43 

South 

 American 

 Bituminous 

10–15-min 9.93–11.72 10.34–11.79 NA NA NA

 24-hour 9.13 NT NA NA NA

 1 M KCl 10.66 NT NA NA NA

Western 

Bituminous 

10–15-min 11.52–13.00 NA NA NA NA

 24-hour 10.38–12.65 NA NA NA NA

 1 M KCl 11.40–12.83 NA NA NA NA

Subbituminous 10–15-min 11.89–12.56 10.65–11.47 NA NA NA

 24-hour 12.27–12.56 10.95–11.90 NA NA NA

 1 M KCl 11.96–12.62 10.48–11.16 NA NA NA

Lignite 10–15-min 11.20–12.84 11.74–12.69 12.39–12.85 12.04–12.19 6.69–11.67 

 24-hour 10.50–12.74 11.86–12.61 12.29–12.77 11.77 10.52–12.00 

 1 M KCl 11.05–12.84 12.38–12.84 12.82 NT 9.42–11.73 
45 

 Table 5-17. Fly Ash Samples Exhibiting a Greater-than-One-pH-Unit Change 

 over a 24-hour Period 

ID No. Sample Type Coal Type 

10–15-

min pH 

24-hr 

pH 

pH 

Change LOI, % 

05-040 Fly ash + AC (postprimary PCD) Lignite 7.03 11.36 4.33 9.68 

03-083 Fly ash Eastern 

bituminous 

4.75 9.00 4.25 1.20 

06-001 Fly ash + AC (postprimary PCD) Lignite 7.20 11.37 4.17 11.62 

05-024 Fly ash + AC (postprimary PCD) Lignite 7.43 11.41 3.98 9.45 

03-004 Fly ash Eastern 

bituminous 

4.54 7.08 2.54 3.34 

05-013 Fly ash + AC (postprimary PCD) Lignite 9.00 11.33 2.33 13.24 

03-006 Fly ash Eastern 

bituminous 

4.82 6.78 1.96 5.24 

03-005 Fly ash Eastern 

bituminous 

4.45 5.88 1.43 3.60 

03-007 Fly ash Eastern 

bituminous 

4.38 5.52 1.14 4.48 

05-018 Fly ash Eastern 

bituminous 

7.42 8.49 1.07 3.01 

04-006 Fly ash Western 

bituminous 

11.56 10.38 −1.18 1.42 

02-076 Fly ash South 

American 

bituminous 

10.38 9.13 −1.25 21.06 

02-072 Fly ash Eastern 

bituminous 

10.09 8.83 −1.26 5.29 

02-070 Fly ash Eastern 

bituminous 

9.98 8.50 −1.48 5.87 

 The fly ash samples that exhibited an increase in pH from the 10–15-minute measurement 

to the 24-hour measurement were either bituminous or lignite samples, but the lignite samples all 

contained AC from injection after the primary PCD and an associated relatively high LOI. The 

10–15-minute pH for the lignite fly ash + AC samples was 7 or higher, and the increase in pH at 

24 hours ranged from 2.3 to 4.3 units. The bituminous fly ash samples had 10–15-minute pH 

values of ~4.4–7.4 and had LOI values of 1.2%–5.2%. Most of these samples exhibited a pH 

increase of ~1–2 units; however, the sample with the lowest LOI (1.2%) had an increase of over 

4 units. For the lignite fly ash + AC samples, the reason for the increases noted was not evident 

but may be associated with the AC present, hydration reactions, or solubility of surface coatings 

or specific phases in the sample. 
46 

 Four bituminous fly ash samples exhibited a decrease in pH from the 10–15-minute 

measurement to the 24-hour measurement. Solubility of specific phases or coatings or hydration 

reactions may also have an impact on these samples and cause changes to the pH. This decrease 

could also be due to uptake of CO2 from the atmosphere. 

 These pH development data are interesting because pH is a primary factor in leachability.

It has been shown that at pH values over 10.5, ettringite can and will form in fly ash samples. 

This is important because of the fact that ettringite can incorporate numerous oxyanions such as 

borate, chromate, and selenate into its structure, thus rendering them insoluble. It is important, 

especially with alkaline ash types, to know the true equilibrium pH in order to decide if LTL is 

necessary. LTL is always suggested at 18-hour and 30- and 60-day equilibration times in ash 

samples with equilibrium pH values above 10.5. The only exception to this is if mercury is the 

only analyte. Mercury does not appear to be affected by ettringite formation. These data suggest 

that pH measurements for CCBs should include an equilibration time of at least 24 hours. 

 The pH values reported for all FGD–SDA samples (Table 5-18) fell within a narrow range 

regardless of the presence of AC. The pH for these samples is primarily a result of the presence 

of unreacted sorbent, which is present as calcium hydroxide. Calcium hydroxide has a pH of 

12.4, which is very similar to the pH values measured in the FGD–SDA samples. The presence 

of alkaline fly ash may also influence the pH of FGD–SDA samples, but the lack of a separate 

fly ash sample from these systems does not allow a discussion of the impact of the fly ash on pH. 

The pH of the FGD–SDA +EA + AC samples is slightly elevated from the FGD–SDA samples. 

It was hypothesized that the increased pH, while minimal, could be associated with the presence 

of AC or the EA, which was unidentified. 

 The ranges of pH values of FGD materials and liquids are shown in Tables 5-19 and 5-20 

and Appendices H and K. With the exception of the fixated wet FGD materials, the wet FGD 

materials and liquids all exhibited acidic to near-neutral pH. This is due to either complete 

reaction of the alkaline scrubbing material or coating of the alkaline phase with neutral calcium 

sulfate. The fixated wet FGD material likely exhibits an alkaline pH because of the presence of 

fly ash used to fixate the material. 

 Table 5-18. Range of pH in FGD–SDA Samples 

Coal Type pH Test FGD–SDA FGD–SDA + EA + AC 

Subbituminous 10–15-min 12.34–12.41 NA 

 24-hour 12.22 NA 

 1 M KCl 12.53 NA 

Lignite 10–15-min 12.18–12.85 12.51–13.06 

 24-hour 12.50 12.54 

 1 M KCl NT NT 
47 

Table 5-19. Ranges of pH in Wet FGD Material Sample 

 FGD Gypsum Wet FGD Slurry Wet FGD Filtercake Fixated Wet FGD

10–15-min pH 8.07–8.83 7.84–8.95 7.47–8.18 10.87–12.75

24-hour pH 7.72–7.95 8.75 7.70–7.88 10.50–12.43

1 M KCl pH NT NT NT 11.75–12.30

 Table 5-20. Ranges of pH in Liquid from Wet FGD Material Samples 

 FGD Gypsum 

Filtrate

FGD Slurry 

Liquor

FGD Filtercake 

Liquor FGD Filtrate

10–15-min pH 5.40–5.49 6.73–6.78 6.53–7.36 7.20–7.26

24-hour pH 5.20–5.25 7.38 5.92–7.56 8.13–8.17

5.4.4 Carbon Forms 

 It is well known that unburned carbon associated with coal fly ash takes on many different 

morphological forms, three major forms of which are generally recognized. These 

morphologically different carbon forms are inertinite, isotropic coke, and anisotropic coke. Each 

of these forms has distinct and predictable physical properties. Isotropic and anisotropic coke 

have gone through the combustion process and undergone considerable changes including 

melting and reaction with oxygen, while inertinite appears to be relatively unaffected by the 

combustion process. Isotropic cokes represent extensively reacted, nongraphitizable carbon 

particles, and anisotropic cokes represent extensively reacted, more highly aligned carbon 

particles (Maroto-Valer et al., 1999a). In a study of carbon forms associated with Class F fly ash, 

it was found that inertinites exhibit the lowest surface area (15–25 m2

/g), isotropic coke particles 

presented intermediate surface areas (25–35 m2/g), and anisotropic coke exhibited the highest 

surface areas (35–60 m2

/g) (Maroto-Valer et al., 1999b). Therefore, inertinites represent lowdensity, low-surface-area particles; isotropic cokes represent intermediate-density, intermediatesurface-area particles; and anisotropic cokes represent high-density, high-surface-area particles. 

Studies on Class C fly ashes, generally derived from subbituminous and lignite coals, have 

shown much higher surface areas (200–400 m2

/g) (Maroto-Valer et al., 1999b), indicating that 

the properties of fly ashes are not only dependent on petrographic composition, but also on the 

rank of coal from which they are derived (Maroto-Valer et al., 1999b). Probably, in part, due to 

the differences in surface area, the adsorption of mercury has shown the same series with 

anisotropic coke > isotropic coke > inertinite. 

 A limited number of fly ash samples were analyzed to determine carbon forms present 

(Appendix L). A summary of the data collected is shown in Table 5-21, including the types of fly 

ash samples evaluated, the identified dominant carbon forms, and the mercury content of the 

samples. 

 As indicated by the data in Table 5-21, fly ash samples without any AC present had a 

broad range of LOI, which generally reflects the amount of unburned carbon present. While 

other chemical changes can contribute to LOI, these are usually small contributions. The results 
48 

Table 5-21. Number of Samples per Carbon Form with Total Hg and LOI Ranges 

 Fly Ash Fly Ash + AC (Pre-Primary PCD) 

Fly Ash + AC (Post-Primary 

PCD) 

Dominant 

Carbon 

Form 

No. 

Samples 

Hg Range, 

μg/g 

LOI 

Range, % 

No. 

Samples 

Hg Range, 

μg/g 

LOI 

range, % 

No. 

Samples 

Hg 

Range, 

μg/g 

LOI 

Range, % 

Anisotropic 

 Coke 

2 0.607–0.785 2.54–21.2 2 0.289–1.86 0.97–2.47 2 55.6–120 22.2–24.4 

Isotropic 

 Coke 

2 0.440–0.578 1.00–7.48 1 1.09 2.84 0 NA NA 

Inertinite 1 0.097 3.20–3.48 2 0.225–2.22 0.96–4.21 0 NA NA 

Vitrinite 4 <0.01–0.662 0.24–4.54 0 NA NA 0 NA NA 

Unburned 

 Carbon 

5 0.017–0.197 1.20–12.7 1 0.490 1.26–1.29 0 NA NA 

indicated that unburned carbon was the dominant carbon form in most of these samples, with the 

second most prominent form of carbon present being vitrinite, another relatively low-sorbing 

carbon form. The fly ash samples from systems without AC addition also contained the lowest 

concentrations of mercury, and those with unburned carbon, vitrinite, and inertinite as the 

dominant carbon form generally had the lowest mercury content within that sample’s set. 

 Very limited samples of fly ash with AC (fly ash + AC [pre-primary PCD]) and fly ash + 

AC [post-primary PCD]) were available for analyses; however, the data indicate that these 

samples contain more reactive carbon forms. The two samples of fly ash + AC (post-primary 

PCD) evaluated both had anisotropic coke as the dominant carbon form. The LOI of these 

samples was very high as was the mercury content, which is consistent with the presence of a 

high-sorbing carbon form. For the fly ash + AC (pre-primary PCD) samples, three of six samples 

evaluated had either anisotropic or isotropic coke as the dominant carbon form. The LOI and 

mercury contents of these samples were similar to the four samples of fly ash without mercury 

control that had anisotropic and isotropic carbon as the dominant carbon forms. 

 The carbon form data verify that the presence of high-sorbing carbon forms can be an 

indicator of elevated mercury in fly ash samples and that AC contains these high-sorbing carbon 

forms. 

5.5 Laboratory Evaluation of ATE Releases 

5.5.1 Direct Leaching 

 Leaching was performed using multiple tests. As already noted, the methods were TCLP 

(EPA Method 1311, 1992), SGLP, and LTL with 30- and 60-day equilibration periods. Mercury 

and other ATEs were determined on leachates as the sample quantity allowed. Complete leachate 

data are reported in Appendix M. Summaries of leachate data are shown by sample type in 

Tables 5-22 through 5-24. 
49 

Table 5-22. Ranges of Leachate Results for Fly Ash, μg/L 

Element Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA + 

AC (pre-primary 

PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

As <2–336 <2–16.3 <2–15.2 46.3–95.9 8.1–842 

Cd <0.2–8.30 <0.2–1.49 <0.2–0.39 <0.3–2.68 0.85–2.46 

Cr 1.40–277 3.60–560 <2–134 182–211 17.3–680 

Pb <0.001–8.50 <0.001–3.00 <0.001–3.00 <2 <2 

Hg <0.01–0.325 <0.01–0.068 <0.01–0.061 <0.01–0.02 <0.01–0.07 

Ni <2–80.6 <2–23.1 <2–25.2 <2–2.8 <2–23.4 

Se <2–514 <2–147 <2–47.2 <4–97.0 45.2–8620 

pH 3.54–12.81 3.80–12.60 12.21–12.61 11.69–12.01 3.79–11.82 

 Table 5-23. Ranges Leachate Results for FGD–SDA, μg/L 

Element FGD–SDA 

FGD–SDA + EA + AC (preprimary PCD) 

As 2.1–3.5 3.6–4.3 

Cd <0.2–0.59 <0.2–0.2 

Cr 34.6–223 21.8–87.7 

Pb <2 <2 

Hg <0.01–0.095 <0.01–0.012 

Ni <2–39.1 <2–29.3 

Se 11.3–65.8 12.0–24.3 

pH 11.41–12.47 12.41–12.60 

 Table 5-24. Ranges of Leachate Results for Wet FGD Material, μg/L 

Element FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

As <4 <4 <2–3.7 <2–24.0 

Cd <0.2–0.46 <0.3 <0.2–0.830 0.30–0.66 

Cr <2 <1 <2 2.2–4.7 

Pb <2 <0.001 <2 <2–14.3 

Hg <0.01 0.047 <0.01–0.476 <0.01–0.289 

Ni <2–28.4 15.0 6.10–32.1 <2–4.00 

Se 2.70–18.7 65.0 41.0–71.2 <2–3.40 

pH 7.42–8.17 8.02 7.57–8.39 11.31–12.34 

 A leaching topical report was published in August 2005 and can be found in Appendix N. 

Leaching experiments continued after the leaching topical report was published, but the added 

data were consistent with those presented in the topical report and supported the observations 

made. The results for each element included in the study are presented and discussed in detail in 

the following sections. 
50 

5.5.1.1 Mercury 

 Mercury leachate results for fly ash, FGD–SDA, and FGD material samples are reported 

on separately. Total mercury concentrations discussed throughout the section are included in 

Appendix G. 

 The ranges of mercury leachate results for fly ash are reported by leaching test in 

Table 5-25. Table 5-26 shows that data separated by coal type. Figure 5-1 shows the 18-hour 

SGLP mercury leaching data for fly ash samples plotted against the total mercury content of the 

sample. Figure 5-2 shows the 18-hour SGLP mercury leaching data for fly ash + AC and/or EA 

samples plotted against the total mercury content of the sample. 

 For fly ash and fly ash + AC and/or EA, mercury is not readily leachable. Most samples 

have a leachate concentration below the 0.01 μg/L analytical method reporting limit. All fly ash 

sample leachates had mercury concentrations below the 2.0-μg/L primary drinking water (PDW) 

limit. The graphical representations of the mercury leachate data for fly ash and fly ash + AC 

and/or EA samples, as shown in Figures 5-1 and 5-2, also indicated that total mercury content 

does not correlate with leachable mercury. This is true for all leaching methods used in this 

project. The leachability of mercury from fly ash is not expected to impact current fly ash 

management practices. 

 Review of the total mercury content and leachate concentrations for the paired fly ash 

samples indicated that the total mercury concentration increased with the introduction of AC 

(with or without an EA) regardless of the location where the AC was injected (see Tables 5-27–

5-29). The total mercury concentrations of fly ash + AC collected from post-primary PCD 

locations showed the greatest increase over the concentrations measured in the baseline fly ash 

samples. The mercury leachate concentrations reported for the paired fly ash samples do not 

reflect the increased total mercury content, and the mercury leachate concentrations are similar 

for all fly ash samples within the paired sample set for all leaching procedures, time frames, and 

final leachate pH. Most fly ash samples, both the paired sample set and the overall project 

sample set, had mercury leachate results of <0.01, the analytical reporting limit of the method 

used. The total mercury content does not correlate with the mercury leachate concentrations. 

Table 5-25. Ranges of Fly Ash Mercury Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA + 

AC (pre-primary 

PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour 

 SGLP 

<0.01–0.083 <0.01–0.064 <0.01–0.016 <0.01 <0.01–0.03 

30-day 

 LTL 

<0.01–0.113 <0.01 <0.01–0.061 <0.01 <0.01 

60-day 

 LTL 

<0.01–0.325 <0.01–0.068 <0.01–0.016 <0.01–0.02 <0.01–0.028 

TCLP <0.01–0.034 <0.01 NT NT <0.01–0.070 
51 

Table 5-26. Ranges of Fly Ash Mercury Leachate and Leachate pH Results by Coal Type 

and Leaching Test

Coal Type Sample Type 

TCLP Hg 

Leachate and 

pH 

18-hour SGLP 

Hg Leachate 

and pH 

30-day LTL Hg 

Leachate and pH 

60-day LTL Hg 

Leachate and pH 

Eastern 

 Bituminous 

Fly ash <0.01–0.03 

μg/L 

3.54–4.97 

<0.01–0.05 

μg/L 

4.71–12.67 

<0.01–0.104 

μg/L 

9.38–11.49 

<0.01–0.239 

μg/L 

5.55–11.36 

Eastern 

 Bituminous 

Fly ash + AC 

(post-primary 

PCD) 

<0.01–0.07 

μg/L 

3.79–4.76 

<0.01–0.03 

μg/L 

4.00–9.89 

NT NT 

South 

 American 

 Bituminous 

Fly ash <0.01–0.034 

μg/L 

3.89–4.11 

<0.01–0.016 

μg/L 

11.18–11.68 

NT NT 

South 

 American 

 Bituminous 

Fly ash + AC 

(pre-primary 

PCD) 

<0.01 μg/L 

3.80–4.20 

<0.01 μg/L 

10.71–11.71 

NT NT 

Western 

 Bituminous 

Fly ash NT <0.01–0.021 

μg/L 

11.59–12.81 

0.035–0.076 

μg/L 

11.37–12.54 

<0.01–0.087 

μg/L 

11.31–12.52 

Sub- 

 bituminous 

Fly ash NT <0.01–0.023 

μg/L 

12.09–12.49 

<0.01 μg/L 

12.36–12.63 

<0.01–0.325 

μg/L 

12.45–12.58 

Sub- 

 bituminous 

Fly ash + AC 

(pre-primary 

PCD) 

<0.01 μg/L 

5.51–6.56 

<0.01–0.064 

μg/L 

11.08–12.21 

<0.01 μg/L 

11.84–12.46 

<0.01–0.068 

μg/L 

11.85–12.38 

Lignite Fly ash NT <0.01–0.083 

μg/L 

10.95–12.60 

<0.01–0.113 

μg/L 

11.34–12.65 

<0.01–0.124 

μg/L 

11.25–12.54 

Lignite Fly ash + AC 

(pre-primary 

PCD) 

NT <0.01 μg/L 

12.60 

<0.01 μg/L 

12.34 

<0.01 μg/L 

12.40 

Lignite Fly ash + EA + 

AC (preprimary PCD) 

NT <0.01–0.016 

μg/L 

12.34–12.57 

<0.01–0.061 

μg/L 

12.21–12.61 

<0.01–0.016 

μg/L 

12.48–12.59 

Lignite Fly ash + EA NT <0.01 μg/L 

11.94 

<0.01 μg/L 

11.79 

0.011 μg/L 

12.00 

Lignite Fly ash + AC 

(post-primary 

PCD) 

NT <0.01–0.012 

μg/L 

11.00–11.88 

<0.01 μg/L 

11.52–12.05 

<0.01–0.028 

μg/L 

11.43–12.09 
52 

Figure 5-1. Fly ash 18-hour SGLP leachate mercury plotted against total mercury content. 

Figure 5-2. Fly ash + AC and/or EA 18-hour SGLP leachate mercury plotted against total 

mercury content.
53 

 Table 5-27. Paired Samples Mercury 18-hour SGLP and TCLP Leachates and 

 Fundamental Characterization Data 

ID Nos. Sample Type 

Total Hg, 

μg/g 

18-hour SGLP Hg 

Leachate and pH 

TCLP Hg 

Leachate and pH 

02-070 Fly ash 0.194 0.01 μg/L 

10.55 

0.03 μg/L 

3.56 

02-069 Fly ash + ACI (postprimary PCD) 0.742 0.03 μg/L 

9.48 

0.07 μg/L 

3.79 

02-072 Fly ash 0.163 0.02 μg/L 

10.81 

0.02 μg/L 

3.54 

02-071 Fly ash + ACI (postprimary PCD) 0.975 0.01 μg/L 

9.89 

<0.01 μg/L 

4.06 

02-076 Fly ash 0.607 0.016 μg/L 

11.18 

<0.01 μg/L 

3.89 

03-009 Fly ash + ACI (preprimary PCD) NT <0.01 μg/L 

11.71 

<0.01 μg/L 

4.20 

03-010 Fly ash + ACI (preprimary PCD) NT <0.01 μg/L 

10.71 

<0.01 μg/L 

3.80 

Table 5-28. Paired Mercury Leachates and Fundamental Characterization Data of Fly Ash 

Samples with Enhancing Agent and ACI 

ID Nos. Sample Type 

Total Hg, 

μg/g 

18-hour SGLP 

Hg Leachate 

and pH 

30-day LTL 

Hg Leachate 

and pH 

60-day LTL 

Hg Leachate 

and pH 

04-035 Fly ash 0.159 0.081 μg/L 

12.60 

0.02 μg/L 

12.65 

<0.01 μg/L 

12.54 

04-036 Fly ash + EA + ACI (preprimary PCD) 0.287 0.011 μg/L 

12.56 

<0.01 μg/L 

12.61 

<0.01 μg/L 

12.59 

05-001 Fly ash <0.01 <0.01 μg/L 

12.42 

0.011 μg/L 

12.32 

0.011 μg/L 

12.39 

05-003 Fly ash + EA + ACI (preSDA) 0.565 <0.01 μg/L 

12.34 

0.043 μg/L 

12.30 

0.015 μg/L 

12.49 

05-005 Fly ash 0.431 <0.01 μg/L 

11.69 

<0.01 μg/L 

11.74 

<0.01 μg/L 

11.83 

05-017 Fly ash + EA 0.717 <0.01 μg/L 

11.94 

<0.01 μg/L 

11.79 

0.011 μg/L 

12.00 

 In leachate from FGD–SDA samples (Table 5-30), mercury was measured either at very 

low concentrations or was below the analytical reporting limit. Samples collected with and 

without mercury emission controls in place had similar mercury leachate concentrations. These 

data indicated that current management practices can continue to be used for these samples. The 

paired sample data (as seen in Table 5-31) showed a definite increase in the total mercury 

content of the test sample over the baseline samples; however, no significant difference was 

noted in the mercury leachate concentrations for the FGD–SDA paired samples. No correlation 

between the total and leachate mercury concentrations was observed. 
54 

 Table 5-29. Paired Mercury Leachates and Fundamental Characterization 

 Data of Fly Ash Samples with AC

ID Nos. Sample Type 

Total 

Hg, μg/g

18-hour SGLP 

Hg Leachate 

and pH 

30-day LTL 

Hg Leachate 

and pH 

60-day LTL 

Hg Leachate 

and pH 

03-061 Fly ash 0.578 0.012 μg/L 

12.45 

<0.01 μg/L 

12.63 

0.325 μg/L 

12.58 

03-060 Fly ash + AC (preprimary PCD) 1.86 0.015 μg/L 

12.18 

<0.01 μg/L 

12.46 

0.037 μg/L 

12.38 

05-038 Fly ash 0.104 <0.01 μg/L 

11.85 

<0.01 μg/L 

12.00 

<0.01 μg/L 

12.09 

05-013 Fly ash + AC (postprimary PCD) 39.0 <0.01 μg/L 

11.45 

<0.01 μg/L 

11.66 

<0.01 μg/L 

11.61 

05-023 Fly ash + AC (postprimary PCD: high 

ash) 

12.7 <0.01 μg/L 

11.85 

<0.01 μg/L 

12.05 

<0.01 μg/L 

12.09 

05-024 Fly ash + AC (postprimary PCD) 35.9 <0.01 μg/L 

11.51 

<0.01 μg/L 

11.67 

<0.01 μg/L 

11.68 

05-025 Fly ash + AC (postprimary PCD: high 

ash) 

12.6 <0.01 μg/L 

11.88 

<0.01 μg/L 

12.04 

<0.01 μg/L 

12.07 

05-040 Fly ash + AC (postprimary PCD) 44.5 <0.01 μg/L 

11.47 

<0.01 μg/L 

11.55 

<0.01 μg/L 

11.54 

06-001 Fly ash + AC (postprimary PCD) 64.5 <0.01 μg/L 

11.39 

<0.01 μg/L 

11.52 

<0.01 μg/L 

11.47 

 Table 5-30. Ranges of FGD–SDA Mercury Leachate 

 Results by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP <0.01 <0.01 

30-day LTL <0.01–0.050 <0.02 

60-day LTL 0.013–0.043 0.012 

Table 5-31. Paired FGD–SDA Mercury Leachates and Fundamental Characterization Data 

ID Nos. Sample Type 

Total 

Hg, μg/g

18-hour SGLP 

Hg Leachate 

and pH 

30-day LTL 

Hg Leachate 

and pH 

60-day LTL Hg 

Leachate and 

pH 

05-002 FGD–SDA <0.01 <0.01 μg/L 

12.40 

0.050 μg/L 

12.32 

0.013 μg/L 

12.47 

05-004 FGD–SDA + EA + AC 

(pre-SDA) 

0.332 <0.01 μg/L 

12.43 

<0.02 μg/L 

12.48 

0.012 μg/L 

12.60 
55 

 Mercury leachate concentrations from the FGD materials noted in Table 5-32 were also 

generally low, but the 18-hour SGLP results for the wet FGD filtercake and fixated wet FGD 

material were higher than the other wet FGD materials, FGD–SDA, and fly ash samples. 

Leachate data indicated that short-term mercury leachate concentrations from sulfite-rich wet 

FGD samples were somewhat elevated over the long-term mercury leachate concentrations, as 

also noted in Table 5-32. Leaching of FGD gypsum resulted in the lowest mercury leachate 

concentrations of all the wet FGD material samples. The total mercury concentrations for all wet 

FGD material samples were very similar, but the data were insufficient to determine if there is a 

correlation between total and leachate mercury concentrations. Further evaluation of a wide 

variety of wet FGD materials should include careful identification of the sample type and 

location as well as factors that may impact the mercury and ATE concentrations and leaching 

behavior. 

5.5.1.2 Arsenic 

 The ranges of arsenic leachate results by leaching test are reported for all project fly ash 

samples in Table 5-33, FGD–SDA samples in Table 5-34, and wet FGD samples in Table 5-35. 

 Table 5-32. Ranges of Wet FGD Material Mercury Leachate Results by Leaching 

 Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <0.01 0.047 0.404–0.476 0.237–0.289 

30-day LTL NT NT <0.01 <0.01 

60-day LTL <0.01 NT <0.01 <0.01 

Table 5-33. Range of Fly Ash Arsenic Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour SGLP <2–266 <4–16.3 <2–15.2 NT 20.2–842 

30-day LTL <4–305 <2–9.9 <4–6.4 46.3 8.1–30.4 

60-day LTL <2–336 <2–11.7 <2–7.5 73.0–95.9 10.4–27.3 

 Table 5-34. Ranges of FGD–SDA Arsenic Leachate Results 

 by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP 2.10–3.50 4.30 

30-day LTL 2.60–3.30 3.60 

60-day LTL 2.20–2.30 3.80 
56 

 Table 5-35. Ranges of Wet FGD Material Arsenic Leachate Results by Leaching 

 Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <4 <4 <4 4.90–7.00 

30-day LTL NT NT 3.50 5.20–24.0 

60-day LTL <2 NT <2 <2–19.1 

 Arsenic leachate concentrations of fly ash + AC (pre-primary PCD), fly ash + EA + AC 

(pre-primary PCD), and fly ash + EA all were measured to be within the range reported for 

leachates from fly ash only. Total arsenic (Appendix G) was not elevated in any samples with 

AC or EA present. However, for the fly ash + AC collected post-primary PCD, several samples 

collected from a lignite-fired system had arsenic leachate concentrations significantly higher than 

the fly ash only, even though total arsenic concentrations were similar. The leaching data from 

this paired sample set as noted in Figure 5-3. 

 The arsenic-leaching data for one set of paired fly ash samples is shown in Figure 5-3 with 

the individual data from the 18-hour SGLP and 30- and 60-day LTL leaching test indicated for 

each sample. These samples were all collected from a system demonstrating injection of AC 

after the primary PCD. These data show a leaching profile typical of alkaline fly ash samples for 

elements that are present as oxyanions (arsenic, boron, selenium, and others). As shown, the 

arsenic leachate concentration decreases with time. These specific samples also show an increase 

Figure 5-3. Arsenic 18-hour SGLP and 30- and 60-day LTL leaching data for a paired sample 

set. 
57 

in the arsenic leachate concentrations in the test samples as compared to the baseline sample 

even though the total arsenic concentrations in these samples were all similar. These data suggest 

that the AC may impact the leaching profile to facilitate increased arsenic release; however, 

other paired fly ash samples with AC injected post-primary PCD did not exhibit similar trends. 

This observation should be considered as various CCBs from mercury emission controls are 

evaluated for leaching characteristics, especially for arsenic since the arsenic limit for PDW was 

recently lowered to 10 μg/L. 

 Total arsenic concentrations were similar for FGD–SDA samples evaluated, and the 

arsenic leachate concentrations were also similar, as shown in Table 5-34. Arsenic mobility from 

all FGD–SDA samples evaluated was low. 

 The arsenic-leachate concentrations for the various wet FGD materials noted in Table 5-35 

were also very low, with the highest values noted for the fixated wet FGD material. The LTL 

results also indicated an increase in arsenic leaching with time for the fixated wet FGD materials. 

5.5.1.3 Cadmium 

 The ranges of cadmium leachate results by leaching test are reported in Tables 5-36 

through 5-38 for fly ash samples, FGD–SDA samples, and wet FGD material samples, 

respectively. 

 For all sample types, cadmium leachate concentrations were generally low, but the highest 

cadmium leachate values were reported for the fly ash samples without any emission controls in 

place. No increase in total cadmium content was noted with the presence of AC or EA. Cadmium 

leachate data are similarly low, varying within the limits of the test and analysis, for all fly ash 

samples collected with mercury emission controls in place, all FGD–SDA materials, and all wet 

FGD materials. The cadmium leachate values for the fly ash samples collected under mercury 

emission control conditions fell within the range of cadmium leachate concentrations for fly ash 

only. As observed in previous work, no trend is noted for cadmium leachate concentrations over 

LTL. 

Table 5-36. Ranges of Fly Ash Cadmium Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour 

 SGLP 

<0.2–8.08 <0.2–1.49 0.27–0.39 NT 0.99–1.87 

30-day 

 LTL 

<0.2–7.64 <0.2–1.06 <0.2 2.40 0.85–1.99 

60-day 

 LTL 

<0.2–8.30 <0.2–0.90 <0.2 <0.3–2.68 0.85–2.46 
58 

 Table 5-37. Ranges of Fly Ash + FGD–SDA Material Cadmium 

 Leachate Results by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP 0.22–0.37 0.20 

30-day LTL <0.2–0.58 <0.2 

60-day LTL 0.20–0.59 <0.2 

 Table 5-38. Ranges of Wet FGD Material Cadmium Leachate Results by Leaching 

 Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <0.2–0.46 <0.3 <0.2 0.43–0.44 

30-day LTL NT NT 0.83 0.30–0.66 

60-day LTL <0.2 NT 0.47 0.37–0.50 

5.5.1.4 Chromium 

 The ranges of chromium leachate results for all project sample types by leaching test are 

reported in Tables 5-39 through 5-41. 

 A comparison of all fly ash samples for total chromium versus leachate chromium was 

made (Appendix N), and results indicated that there may be an increased chromium leachate 

concentration for some fly ash samples with mercury control. However, the paired samples 

collected under this mercury emission control configuration do not provide any indication of 

increased total chromium concentrations in the test samples over the baseline sample (see 

Table 5-10). Additionally, the leaching results for these paired samples did not show any changes 

in the leaching profile for test samples compared to the baseline sample. Chromium leachate 

concentrations were generally similar for fly ash samples with and without mercury controls in 

place, but the samples of fly ash + AC did yield some leachates with higher chromium 

concentrations. For paired samples, it was typical that changes in leachate concentrations noted 

over the LTL series results were the same for baseline and test samples. In some cases, 

chromium leachate concentrations decreased with leaching time and, in some cases, the 

chromium leachate concentrations increased with leaching time. No general trend was identified. 

The decreases in chromium leachate concentrations with time were consistent with formation of 

secondary hydrated phases, but even though the pH of all samples in the paired sample set was 

typical for these reactions to occur, the data were inconclusive. 

 For FGD–SDA materials, the paired samples collected with mercury emission controls in 

place exhibited lower chromium leachate concentrations than those collected without mercury 

emission controls in place. For both the baseline and test samples, the 18-hour leachate had 

lower chromium concentrations than the long-term leachates. 
59 

Table 5-39. Ranges of Fly Ash Chromium Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour 

 SGLP 

1.4–174 <50–560 <2–67.6 NT 17.3–410 

30-day 

 LTL 

<2–265 3.6–147 <2–133 203 152–650 

60-day 

 LTL 

<2–277 5.2–138 2.1–134 182–211 155–680 

 Table 5-40. Ranges of FGD–SDA Chromium Leachate 

 Results by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP 34.6–116 21.8 

30-day LTL 113–215 67.7–78.0 

60-day LTL 132–223 87.7 

 Table 5-41. Ranges of Wet FGD Material Chromium Leachate Results by 

 Leaching Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <2 <2 <2 3.0–4.7 

30-day LTL NT NT <2 2.2–3.1 

60-day LTL <2 NT <2 2.4–3.3 

 Chromium concentrations were significantly lower in the wet FGD material leachates, but 

all wet FGD materials leached chromium at similarly low levels. 

5.5.1.5 Lead 

 The ranges of lead leachate results are reported for fly ash samples in Table 5-42, FGD–

SDA samples in Table 5-43, and wet FGD material samples in Table 5-44. 

 Lead leachate data indicated that nearly all leachate lead concentrations were below the 

analytical reporting level. In one paired sample set, the baseline sample had long-term leachate. 

The lead leachate results were consistent with data from previous studies and were generally 

very low. 
60 

Table 5-42. Ranges of Fly Ash Lead Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour 

 SGLP 

<2 <2 <2–3.0 NT <2 

30-day 

 LTL 

<0.001–3.6 <2–3.0 <2 <2 <2 

60-day 

 LTL 

<0.001–8.5 <2–2.4 <2 <2 <2 

 Table 5-43. Ranges of FGD–SDA Material Lead 

 Leachate Results by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP <2 <2 

30-day LTL <2 <2 

60-day LTL <2 <2 

 Table 5-44. Ranges of Wet FGD Material Lead Leachate Results by Leaching Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <2 <0.001 <2 6.60–14.3 

30-day LTL NT NT <2 <2 

60-day LTL <2 NT <2 <2 

5.5.1.6 Nickel 

 Nickel-leaching data are presented in Tables 5-45 through 5-47. Results are shown for fly 

ash samples, FGD–SDA samples and wet FGD material samples, and the SGLP–LTL tests used. 

An early evaluation of total nickel content (Appendix G) compared to leachate nickel content for 

all fly ash samples indicated that fly ash + AC samples exhibited reduced leaching of nickel (see 

Appendix N). Continued laboratory evaluations indicated that this observation was not supported 

by the nickel-leaching data on paired fly ash samples. Nickel concentrations generally decrease 

over leaching time. Nickel usually does not participate in reactions that form secondary hydrated 

phases. 

 Nickel-leaching results for FGD–SDA materials also indicated a decrease in leachate 

nickel concentrations with leaching time. The SGLP leachate nickel concentrations were higher 

than those reported for fly ash samples even though the total nickel content of fly ash samples 

and FGD–SDA materials was similar, and baseline fly ash samples exhibited the highest 

measured total nickel content. 
61 

Table 5-45. Ranges of Fly Ash Nickel Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour 

 SGLP 

<2–80.6 <2–23.1 <2–25.2 NT <2–23.4 

30-day 

 LTL 

<2–10.6 <2–5.4 <2–8.2 2.8 4.4–7.1 

60-day 

 LTL 

<2–70.0 <2–5.3 <2–5.4 <4 2.9–5.1 

 Table 5-46. Ranges of FGD–SDA Nickel Leachate Results by 

 Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP 16.4–39.1 29.3 

30-day LTL <4 <4 

60-day LTL <2 <2 

 Table 5-47. Ranges of Wet FGD Material Nickel Leachate Results by Leaching 

 Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP <2–28.4 15.0 6.1–7.4 <2 

30-day LTL NT NT 32.1 <2–4.0 

60-day LTL 10.1–12.6 NT 25.4 2.1–3.7 

 Leachate nickel concentrations for wet FGD materials were similar to those for most fly 

ash samples and the FGD–SDA samples. 

5.5.1.7 Selenium 

 Selenium was the only ATE other than mercury identified as having increased total 

concentration in some fly ash + AC samples. Specifically, fly ash + AC samples where the AC 

was injected post-primary PCD exhibited an elevated total selenium content compared to the 

baseline for the single paired sample set of that type. Other fly ash paired samples that had the 

AC injected before the primary PCD did not exhibit this increase in total selenium content; 

however, the increase noted for the fly ash/fly ash + AC (post-primary PCD) samples and the 

properties of selenium raised interest in the selenium-leaching data. The ranges of selenium 

leachate results by leaching test for fly ash, FGD–SDA, and wet FGD samples are reported in 

Tables 5-48 through 5-50, respectively. 
62 

Table 5-48. Ranges of Fly Ash Selenium Leachate Results by Leaching Test, μg/L 

Test Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA + 

AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

18-hour SGLP 2.1–412 8.4–147 19.9–47.2 NT 99.3–8620 

30-day LTL <2–489 <2–100 <2–27.2 97.0 47.7–312 

60-day LTL <2–514 3.8–114 <2–30.3 <4–50.9 45.2–199 

 Table 5-49. Ranges of FGD–SDA Selenium Leachate Results 

 by Leaching Test, μg/L 

Test FGD–SDA 

FGD–SDA + EA + AC 

(pre-primary PCD) 

18-hour SGLP 11.3–65.8 24.3 

30-day LTL 12.0–65.2 12.0–13.2 

60-day LTL 14.4–53.1 17.0 

Table 5-50. Ranges of Wet FGD Material Selenium Leachate Results by Leaching 

Test, μg/L 

Test FGD Gypsum 

Wet FGD 

Slurry 

Wet FGD 

Filtercake 

Fixated Wet 

FGD 

18-hour SGLP 3.3–18.7 65.0 41.0–71.2 2.1–2.70 

30-day LTL NT NT 55.2 2.4–3.40 

60-day LTL 2.7–8.2 NT 45.3 <2–2 

5.5.2 Vapor-Phase Transport 

 Two types of vapor-phase transport (release) experiments were performed for this project: 

long-term ambient-temperature release experiments and elevated-temperature release 

experiments. These experiments only measured mercury releases. No other ATEs were 

determined. 

5.5.2.1 Long-Term Ambient-Temperature Release 

 Over the course of this project, the experimental results and information obtained through 

the Year 1 field task, from documents assembled, and through discussions with other research 

groups and sponsors, it became apparent that the term “release” did not always describe the 

results of the ambient-temperature vapor-phase experimental results. The results of the ambienttemperature vapor-phase transport experiments were reported as either mercury released or 

sorbed by the solid sample tested. 

 All samples included in the ambient-temperature experiments and the results are included 

in Appendix O. The experimental results are presented in sample sets because the experimental 

protocol required significant physical space and, therefore, limited the number of samples that 

could be evaluated at one time. Four sample sets were evaluated for mercury captured in the 
63 

analytical traps typically measured three times over the course of the experiment. The 

experiments were usually run for approximately 200 days, but selected samples were allowed to 

run for longer durations because of sample characteristics or release profiles. In the summary 

tables for this section, results for paired samples are highlighted. The tables of summary data 

include results of the two replicates of each sample expressed in two ways: 

• Cumulative % Hg sorption or release refers to the amount of mercury sorption or 

release based on the blank value measured over the entire experiment reported as a 

percentage of the total mercury concentration of the sample. 

• Years to release 100% Hg on CCB at measured rate is a calculation of the number of 

years required to release 100% of the total mercury content on the CCB at the rate of 

release measured over the experiment. 

 The first sample set evaluated comprised 12 samples and included fly ash, fly ash + AC 

(pre-primary PCD), and FGD–SDA samples from eastern bituminous, Powder River Basin 

(PRB) subbituminous, and lignite coal. One paired sample set (Samples 03-061 and 03-060) was 

evaluated. The samples and a summary of the results are shown in Table 5-51. 

 The results collected from Sample Set 1 are also shown graphically in Figure 5-4. Over the 

entire 194-day period of the experiment, five samples showed overall mercury release and seven 

samples showed overall mercury sorption. The release of mercury, expressed as pg/g/day, was 

less for most samples in the final 90-day collection period than for the previous 90-day collection 

period. The observed variability was attributed to the variability inherent in the analysis of the 

extremely low concentrations of mercury captured by and desorbed from the gold-coated 

analytical traps. 

 Samples included in Sample Set 2 and a summary of the results obtained are included in 

Table 5-52, and results are presented graphically in Figure 5-5. The sample set comprised seven 

samples including fly ash, fly ash + AC (post-primary PCD), fly ash + EA + AC (pre-primary 

PCD), and wet FGD filtercake from eastern bituminous, western bituminous, and lignite coal. 

One paired sample set (Samples 04-035 and 04-036) was evaluated. 

 In Sample Set 2, all fly ash samples sorbed mercury regardless of the presence of AC. The 

results from Sample Set 2 indicated that the release of mercury from the wet FGD filtercake 

sample (03-082) was higher than any releases measured for fly ash samples. Evaluation of this 

sample continued past that of the fly ash samples. 

 Based on this observation, Sample 03-082 was reevaluated in Sample Set 3. Also included 

in Sample Set 3 were fly ash, fly ash + EA + AC (pre-primary PCD), FGD–SDA, FGD–SDA + 

EA + AC (pre-SDA), and FGD gypsum from eastern bituminous, PRB subbituminous, and 

lignite coal. Two paired sample sets were evaluated. These included a fly ash pair (Samples 05-

001 and 05-003) and an FGD–SDA pair (Samples 05-002 and 05-004) from the same mercury 

control technology test. Results for Sample Set 3 are presented in Table 5-53. The results of the 

first 187 days of testing are displayed graphically in Figure 5-6. 
64 

Table 5-51. Long-Term Ambient-Temperature Sample Set 1 Summary (Positive values indicate release, and values indicate sorption of mercury. Duplicate bottles are represented.)

 Replicate 1 ReplicID No. Sample Type Coal Type 

Total 

Hg on 

CCB, 

μg/g 

Exp. 

Duration, 

Days 

Cumulative 

% Hg 

Sorption or 

Release 

Years to 

Release 100% Hg on CCB at 

Measured Rate 

Cumulative 

% Hg 

Sorption or 

Release 

Y

C

01-002 Fly ash E. bit. 0.187 194 −0.000153 NA – sorbing −0.000157 03-006 Fly ash E. bit. 0.194 194 −0.000110 NA – sorbing −0.0000845 99-456 Fly ash PRB sub. 1.39 194 −0.0000233 NA – sorbing −0.0000109 01-008 Fly ash PRB sub. 1.22 194 0.0000037 14,472,785 0.0000000 N03-061* Fly ash PRB sub. 0.578 194 0.0000076 6,965,200 −0.0000330 03-060 Fly ash + AC (preprimary PCD) PRB sub. 1.86 194 0.0000007 74,619,320 0.0000021 03-017 Fly ash + AC (preprimary PCD) Lignite 0.225 194 0.0000045 118,14,972 −0.0000966 03-018 Fly ash + AC (preprimary PCD) Lignite 0.289 194 0.0000049 10,817,569 −0.000122 03-062 Fly ash + AC (preprimary PCD) Lignite 0.490 194 0.0000031 17,214,465 0.0000004 99-188 FGD–SDA PRB sub. 0.112 194 0.0000026 20,144,056 -0.000657 00-048 FGD–SDA Lignite 0.361 194 −0.0000674 NA – sorbing 0.0000018 01-011 FGD–SDA Lignite 2.55 194 0.0000006 82,875,125 0.0000008 

* Highlighted samples are paired samples. 
65 

Table 5-52. Long-Term Ambient-Temperature Sample Set 2 Summary (Positive values indicate release, and indicate sorption of mercury. Duplicate bottles are represented.)

 Replicate 1 ID No. Sample Type 

Coal 

Type 

Total Hg 

on CCB, 

μg/g 

Exp. 

Duration, 

Days 

Cumulative % 

Hg Sorption or 

Release 

Years to Release 

100% Hg on CCB 

at Measured Rate 

Cumulative 

Hg Sorption 

Release 

04-054 Fly ash + AC (postprimary PCD) E. bit. 17.7 188 −0.0000008 NA – sorbing −0.0000012 04-006 Fly ash W. bit. 0.144 188 −0.000126 NA – sorbing −0.000235 04-007 Fly ash W. bit. 0.521 188 −0.0000685 NA – sorbing −0.0000168 04-035* Fly ash Lignite 0.159 188 −0.0000646 NA – sorbing −0.0000763 04-036 Fly ash + EA + AC 

(pre-primary PCD) 

Lignite 0.287 188 −0.0000392 NA – sorbing −0.0000434 

04-067 Fly ash + EA + AC 

(pre-primary PCD) 

Lignite 0.640 188 −0.0000246 NA – sorbing −0.0000280 

03-082 Wet FGD filtercake E. bit. 0.248 699 0.609 315 0.448 

* Highlighted samples are paired samples.
66 

Figure 5-4. Sample Set 1 (194-day) long-term ambient-temperature mercury release or sorption 

as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate 

sorption of mercury. Duplicate bottles are represented. 

Figure 5-5. Sample Set 2 (188-day) long-term ambient-temperature mercury release or sorption 

as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate 

sorption of mercury. Duplicate bottles are represented. 
67 

Figure 5-6. Sample Set 3 (187-day) long-term ambient-temperature mercury release or sorption 

as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate 

sorption of mercury. Duplicate bottles are represented. Sample 03-082 is displayed on a 

secondary axis. 

 All fly ash samples in Sample Set 3 sorbed mercury. The FGD gypsum and wet FGD 

filtercake samples released mercury, with the wet FGD filtercake releasing at a rate of 

approximately over 100 times that of the FGD gypsum in the first 187 days of testing. The 

mercury determinations indicated that mercury release was continuing at that point, so the 

exposure to ambient air was continued on all FGD material samples and mercury release was 

determined approximately every 45–60 days. 

 The cumulative mercury release for all the wet FGD material samples was higher than for 

any other samples evaluated. The rate of mercury vapor release was also higher than fly ash 

samples. After extensive exposure to ambient air, some of the wet FGD material samples, 

showed an indication of sorption of mercury. 

 Results for Sample Set 4 are shown in Table 5-54. This sample set included a set of paired 

fly ash samples, with 05-038 being the baseline sample, collected from a system where AC was 

injected after the primary PCD. The paired fly ash + AC samples in the set were test samples that 

had high or low ash content and varying levels of AC present. The remaining two samples were 

FGD gypsum samples from the same plant, where Sample 04-082 was collected when the SCR 

was on and Sample 04-083 was collected when the SCR was off. 
68 

Table 5-53. Long-Term Ambient-Temperature Sample Set 3 Summary (Positive values indicate release, and indicate sorption of mercury. Duplicate bottles are represented.) 

 Replicate 1 RID No. Sample Type 

Coal 

Type 

Total Hg 

on CCB, 

μg/g 

Exp. 

Duration, 

Days 

Cumulative % 

Hg Sorption or 

Release 

Years to Release 

100% Hg on CCB 

at Measured Rate 

Cumulative % 

Hg Sorption o

Release 

04-029 Fly ash PRB 

sub. 

0.261 187 −0.0000304 NA – sorbing −0.0000333 

04-044 Fly ash Lignite 0.878 187 −0.0000245 NA – sorbing −0.0000129 05-001* Fly ash Lignite <0.01 187 −0.00238 NA – sorbing −0.00392 05-003 Fly ash + EA + 

AC (pre-primary 

PCD) 

Lignite 0.565 187 −0.0000234 NA – sorbing −0.0000072 

05-002 FGD–SDA Lignite <0.01 187 −0.00548 NA – sorbing −0.00119 05-004 FGD–SDA + EA 

+ AC (pre-SDA) 

Lignite 0.332 187 −0.0000611 NA – sorbing −0.0000409 

03-065 FGD gypsum E. bit. 0.044 473 0.00756 17,133 0.0111 05-009 FGD gypsum E. bit. 0.032 473 0.0239 5,430 0.0190 03-082 Wet FGD 

filtercake 

E. bit. 0.248 472 1.07 120 0.867 

03-082 Wet FGD 

filtercake 

E. bit. 0.248 476 0.866 151 0.963 

* Highlighted samples are paired samples.
69 

Table 5-54. Long-Term Ambient-Temperature Sample Set 4 Summary (Positive values indicate release, and indicate sorption of mercury. Duplicate bottles are represented.) 

 Replicate 1 ID No. Sample Type 

Coal 

Type 

Total Hg 

on CCB, 

μg/g 

Exp. 

Duration, 

Days 

Cumulative 

% Hg 

Sorption or 

Release 

Years to 

Release 100% Hg on CCB at 

Measured Rate 

Cumulativ

% Hg 

Sorption o

Release 

05-038* Fly ash Lignite 0.104 187 0.0000293 1,747,138 −0.00005305-013 Fly ash + AC (post-primary 

PCD) 

Lignite 39.0 187 0.0000001 388,756,048 0.000000

05-023 Fly ash + AC (post-primary 

PCD: high ash) 

Lignite 12.7 187 0.0000003 173,663,704 0.0000004 

05-024 Fly ash + AC (post-primary 

PCD) 

Lignite 35.9 187 −0.0000001 NA – sorbing −0.000000

05-025 Fly ash + AC (post-primary 

PCD: high ash) 

Lignite 12.6 187 −0.0000017 NA – sorbing −0.000001

05-040 Fly ash + AC (post-primary 

PCD) 

Lignite 44.5 187 0.0000000 6,414,372,585 −0.000000

06-001 Fly ash + AC (post-primary 

PCD) 

Lignite 64.5 187 −0.0000003 NA – sorbing −0.000000

04-082 FGD gypsum E. bit. 0.0427 200 8.41 6.51 8.38 04-083 FGD gypsum E. bit. 0.103 200 0.381 144 0.282 

* Highlighted samples are paired samples.
70 

 The fly ash and fly ash + AC samples in Sample Set 4 generally sorbed mercury or showed 

very low releases. Although Sample 04-082 (SCR on) had a lower total mercury concentration 

than Sample 04-083 (SCR off), it released a greater percentage of mercury. Sample 04-082 

showed the highest mercury release in this project. Figure 5-7 graphically presents the rate of 

mercury release, pg/g/day, from Samples 04-082 and 04-083. This clearly shows that the release 

of mercury from Sample 04-082 is decreasing with time. 

 Review of the results of long-term ambient-temperature release tests indicated that 

mercury might be released from some CCBs at relatively low levels. Fly ash that had unburned 

carbon or AC generally tended to sorb mercury from the ambient air that was introduced into the 

sample container. For fly ash samples, the release of mercury was higher for each sample in the 

first period than in subsequent periods, indicating a reduced rate of release with time. This is due 

to the disruption of the sample and apparatus during sample addition to the container. 

 Wet FGD materials all released mercury at higher levels than any of the fly ash samples 

evaluated, and the calculated number of years to complete release of mercury was the lowest for 

the wet FGD material samples, ranging from 6 to 428 years, while the calculated years to 

complete release were greater than 50M years + for fly ash and FGD–SDA samples evaluated. 

Generally, the rate of release measured in the final testing period was decreasing compared to the 

prior testing period; therefore, the calculated years to release 100% of the total Hg on the CCB is 

likely low. The results indicate that the release or sorption of mercury from fly ash and FGD–

SDA samples is very minute and would cause no adverse impact on the mercury loading to the 

atmosphere. 

Figure 5-7. Long-term ambient-temperature mercury release rate, pg/g/day, from Samples 04-

082 and 04-083. Duplicate bottles are represented. 
71 

5.5.2.2 Desorption at Elevated Temperatures 

 A variety of CCBs were evaluated for the real-time elevated-temperature release of 

mercury. The CCBs were primarily fly ash. Evaluation of FGD materials was limited because of 

analytical interference from the releases of sulfur compounds on sample exposure to elevated 

temperatures. The use of elevated-temperature release of mercury was evaluated as a means of 

determining the speciation of mercury present on CCBs. An elevated-temperature vapor-phase 

mercury release report was published in February 2006 and can be found in Appendix P. This 

report included a complete discussion of the work performed to evaluate the mercury releases 

from CCBs on exposure to elevated temperatures, and the results are summarized here. All 

results can be found in Appendix Q. 

 Thermal desorption curves provided a comparative means of evaluating the 

elevated-temperature release of mercury from a variety of CCBs. Mercury thermal desorption 

curves were generated for 65 CCBs, including 31 fly ash samples and 28 fly ash samples with 

mercury control, two FGD–SDA samples and one FGD–SDA sample with mercury control, and 

three wet FGD materials. Tables 5-55 and 5-56 list the samples evaluated indicating the coal 

source and mercury control. Although three wet FGD materials were tested, analytical 

interferences precluded continued work on FGD materials. 

 The fly ash samples subjected to the elevated-temperature regime typically generated 

either one or two mercury peaks, with four being the maximum number of peaks identified for 

fly ash. As also noted in Table 5-55, mercury was released at temperatures ranging from 256° to 

750°C. Some samples continued to show increasing mercury release at 750°C, so the highest 

peak temperature at which the mercury was released could not be determined. Samples 

exhibiting this continued mercury release at 750°C were predominantly eastern bituminous fly 

ash samples with a LOI greater than 3% or fly ash + AC (post-primary PCD) samples. Samples 

with added AC were more difficult to replicate in part because the mercury was likely associated 

with the carbon particles, and it was more difficult to take a representative sample of fly ash + 

AC, especially with the sample size limitations of the method. Some samples were ground or 

sieved in order to obtain a more homogeneous sample for evaluation. 

 Although the lowest mercury absorbance peak occurred at 256°C for a fly ash sample, the 

initiation of the first mercury release peak was noted before 250°C. Representative mercury 

release curves generated under this task are shown in the report in Appendix P. Examples of 

replicate curves are also shown in the report. An example of a desorption curve with two peaks is 

shown in Figure 5-8. The relatively sharp first peak was typical of most first mercury peaks 

recorded. In curves where two or more peaks were noted, peaks after the initial peak tended to 

show slightly less definition and were usually broader, although the absorption could be higher. 

 Samples with AC were more difficult to evaluate for elevated-temperature mercury 

releases, but sorbents that contained other compounds, such as halogens or sulfur, also offered 

analytical challenges. While sample identifications did not always indicate the exact nature of the 
72 

Table 5-55. Summary of Fly Ash Samples Evaluated in Elevated-Temperature 

Mercury Release Experiments 

Coal Type Sample Type 

No. of 

Samples 

Tested 

No. of 

Peaks 

Range of 

Temp. at 

Peaks, °C 

Total Hg 

Content 

Range, μg/g 

LOI Range, 

% 

Eastern 

 Bituminous 

Fly ash 16 0–4 260–750 <0.01–0.685 0.47–8.46 

 Fly ash + AC 

(post-primary 

PCD) 

6 1–4 262–750 0.742–120 12.6–24.4 

South American 

 Bituminous 

Fly ash 2 1–3 356–750 0.151–0.607 12.7–21.2 

Western 

 Bituminous 

Fly ash 2 1 330–378 0.144–0.521 1.42–2.56 

PRB 

 Subbituminous 

Fly ash 2 1 333–404 0.261–0.578 0.48–1.08 

 Fly ash + AC 

(pre-primary 

PCD) 

4 1–2 302–750 1.09–5.81 2.28–4.14 

Fort Union 

 Lignite 

Fly ash 9 0–3 275–750 <0.01–0.785 0.22–7.48 

 Fly ash + AC 

(pre-primary 

PCD) 

4 1 323–702 0.225–2.22 0.96–4.21 

 Fly ash + EA + 

AC (preprimary PCD) 

3 1–2 306–750 0.287–0.640 1.04–2.49 

 Fly ash + EA 1 0–2 388–684 0.717 1.70 

 Fly ash + AC 

(post-primary 

PCD) 

10 0–3 256–750 0.147–64.5 0.59–13.2 

AC used, samples of this type were expected to produce a thermal curve containing multiple 

peaks. Multiple peaks were noted in a significant number of fly ash samples and were likely due 

to the presence of multiple mercury compounds in the samples (mercury chloride, oxide, nitrate, 

or sulfate) because each compound would be expected to result in a discreet peak on 

vaporization. 

 Elemental mercury is known to sorb as an oxidized species on AC. Additives such as 

sulfur or iodine, for example, could lead to the formation of additional compounds such as 
73 

 Table 5-56. Summary of FGD–SDA and Wet FGD Material Samples Evaluated in 

 Elevated-Temperature Mercury Release Experiments 

Coal Type Sample Type 

No. of 

Samples 

Tested 

No. of 

Peaks 

Range of 

Temp. at 

Peaks, °C 

Total Hg 

Content 

Range, 

μg/g 

LOI 

Range, % 

PRB 

 Subbituminous 

FGD–SDA 1 2–3 270–695 0.0716–

0.131 

2.07 

Fort Union 

 Lignite 

FGD–SDA 1 0 NA <0.01 0.95 

 FGD–SDA + 

EA + AC (preSDA) 

1 1 312–487 0.332 1.12 

Eastern 

 Bituminous 

FGD gypsum 2 1 298–329 0.044–

0.096 

1.22–

1.94 

 Fixated wet 

FGD 

1 3 256–720 0.180 3.11–

3.17 

mercuric sulfide or mercuric iodide. The thermal desorption curves were indicative of the 

following mechanisms of desorption: 

• Elemental mercury and mercuric chloride can desorb unchanged. 

• Other mercury compounds can decompose into their components as would happen with 

mercuric oxide, which would decompose into oxygen and elemental mercury prior to 

desorption. 

 Table 5-57 shows comparative data for fly ash samples subjected to elevated temperature. 

The table shows ranges of the temperatures recorded for the initiation and peak of each mercury 

peak noted for fly ash samples evaluated. The data indicated that the addition of an EA may 

result in fewer peaks to be generated both when used alone or with AC for mercury control. This 

same phenomenon was noted for the FGD–SDA sample shown in Table 5-58. The wet FGD 

materials (results summarized in Table 5-58) produced fewer mercury peaks, and the mercury 

tended to desorb at lower temperatures than noted for samples of fly ash and FGD–SDA. Results 

for FGD–SDA samples tended to be more reproducible than results from fly ash samples. 

5.5.2.3 Mercury Speciation Method 

 An effort was made to use the elevated-temperature apparatus to develop information on 

the species of mercury present on the CCBs tested. The presence of multiple peaks was 

potentially indicative of multiple mercury compounds being desorbed. The mercury speciation 

investigation was initiated with the use of quartz sand and pure quartz powder, spiked with 
74 

Figure 5-8. Typical two-peak mercury desorption curve for fly ash. 

Table 5-57. Range of Fly Ash Peak Mercury Release Temperatures at Elevated 

Temperature, °C 

Peak Fly Ash 

Fly Ash + AC 

(pre-primary 

PCD) 

Fly Ash + EA 

+ AC (preprimary PCD) Fly Ash + EA 

Fly Ash + AC 

(post-primary 

PCD) 

Peak 1 Start 173–645 226–433 275–371 339–372 135–540 

Peak 1 273–750 302–702 324–433 388–406 262–750 

Peak 2 Start 315–705 388–657 350 388 290–710 

Peak 2 346–750 363–750 750 417–684 330–751 

Peak 3 Start 454–709 687 NA NA 362–750 

Peak 3 551–750 704–750 NA 578 411–750 

Peak 4 Start 629 NA NA NA 515–750 

Peak 4 737–747 750 NA NA 705–750 

 Table 5-58. Range of FGD–SDA and Wet FGD Material Peak Mercury 

 Release Temperatures at Elevated Temperature, °C 

Peak FGD–SDA FGD–SDA + EA + AC FGD Gypsum Fixated FGD 

Peak 1 Start 200 (3 times) 264–280 170–250 157 

Peak 1 275–280 312–354 298–329 256 

Peak 2 Start 412–416 NA NA 430 

Peak 2 430–475 487 NA 460 

Peak 3 Start NA NA NA 670 

Peak 3 695 NA NA 720 
75 

mercuric chloride. Quartz was selected as an inert material. A single, sharp peak was recorded 

when the mercuric chloride was added to the quartz sand. However, when mercuric chloride was 

spiked onto pure quartz powder, a double peak was noted. 

 Additional elevated-temperature release experiments were also performed on CCB samples 

spiked with mercury. All samples used in this experiment were fly ash, some of which contained 

AC or EA plus AC from mercury emission control demonstrations. The addition of mercuric 

chloride or elemental mercury vapor to the CCBs resulted in a shift of the mercury release peaks 

noted previously from the samples without any added mercury. The peak temperatures measured 

for spiked CCB samples shifted to higher temperatures for some samples and to lower 

temperatures for other samples. This indicated that the temperature range for mercuric chloride 

in CCBs was too wide for positive identification of a peak as a particular compound. 

 Figures 10 and 11 in Appendix P are an example of a fly ash sample tested as described 

earlier compared to a separate aliquot spiked with mercuric chloride. This was done by mixing a 

single aliquot of the CCB, just less than 2 grams, and dividing it into two small, nearly equal 

portions. One portion was left untreated while the other portion was spiked with 50 μL of an 

ether solution of mercuric chloride containing 10 ng/μL of mercuric chloride. This is equivalent 

to the addition of 370 ng of mercury as mercuric chloride. Spiking was done in this manner to 

minimize nonhomogeneity between the two aliquots of sample. Mercuric chloride spiking of this 

fly ash sample produced an additional peak to those noted on the original fly ash sample. The 

reasons for an additional peak noted in the spiked sample are the same as why a fly ash sample 

may release multiple peaks of mercury. 

 Results indicated that the interaction of mercury and mercury compounds with the CCBs at 

elevated temperatures may preclude speciation using this method on these complex materials. It 

is hypothesized that the first peak that evolves from each CCB is sorbed elemental mercury, 

which can volatilize more readily than mercury compounds. 

5.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport 

 A variety of CCB samples were evaluated for microbiologically mediated mercury releases 

using the methods described in the experimental section and in a report entitled 

“Microbiologically Mediated Mercury and Air Toxic Element Rereleases from Coal Combustion 

By-Products,” and submitted to project sponsors in 2006. The report is included in its entirety in 

Appendix R. The report summarizes the bulk of the work performed under this subtask. The 

work included significant efforts to modify the experimental method and apparatus used to allow 

determination of mercury released from samples of CCB subjected to conditions conducive to 

microbial growth. The samples included in this subtask were primarily fly ash. A complete 

summary of the samples evaluated and identifying information is included in Appendix S. 

 As described in the report noted, six sets of microbiologically mediated experiments were 

completed, and a seventh set was run after preparation of that report. The experimental method 

was designed to determine the leaching and vapor-phase releases from the CCBs under aerobic 

and anaerobic conditions with appropriate buffer to keep the pH of the systems in a range that 

would allow the microbes to reproduce. 
76 

 In keeping with the format used in the report included as Appendix R, a summary of the 

samples and results from Experiment 7 are included here. Table 5-59 provides information on 

the samples evaluated. The samples were all bituminous fly ash without any mercury emission 

controls in place. Results of Experiment 6 indicated that high-pH fly ash typically generated 

from North Dakota lignite or subbituminous coal, cannot be maintained at a pH level that will 

support microbial growth. For that reason, the final experiment focused on fly ash samples with 

near-neutral pH values. 

 Microbiological release Experiment 7 included aerobic and anaerobic glucose-fed 

conditions in triplicate similar to the earlier experiments. A 4-day initial elemental mercury 

release measurement was made for the samples, which was the period between sample and 

buffer addition and bacteria addition to the flask. Observations included possible fungal growth 

within three days of bacteria addition in most sample flasks and a moldy or musty odor in the air 

over the aerobic side of the experimental setup 10 days after bacteria addition. In some samples, 

a gray mold was clearly visible. 

 Analytical data were collected at the end of the monthlong experiment and are reported in 

Tables 5-60–5-62. Prior to preparations necessary for sample analyses, the condition of each 

flask sample was noted after settling of the solids. All anaerobic sample flasks contained a clear 

liquid and had no odor. All aerobic sample flasks contained a dark gray to black, opaque liquid. 

All but one of the aerobic sample flasks (Sample 04-003) had a slightly musty odor. Many of the 

aerobic sample flasks had varying amounts of small white specks or a film that were possibly 

fungus. One of the aerobic flasks for Sample 03-006 had a definite fungus or mold patch on the 

top of the liquid. The liquid samples from the aerobic side of the experiment required the use of a 

centrifuge to separate the liquid and solid enough to filter through a 0.45-μm filter. Eh and pH 

measurements of all filtered liquid samples are reported in Table 5-60. 

 Table 5-61 reports the elemental and organomercury vapor-phase release results in 

pg/g/day. The samples on the aerobic side released more vapor-phase mercury with one 

exception. 

 Results of the mercury and trace element leachate concentrations from that experiment are 

shown in Table 5-62. The aerobic trace element results were reported as the dissolved 

concentration versus the total concentration. Table 5-62 shows several clear differences in 

leachate concentrations of select trace elements between aerobic and anaerobic conditions. Under 

aerobic conditions, concentrations of arsenic, lead, and mercury with one exception, were 

Table 5-59. Microbiological Release Experiment Sample Summary, Experiment 7 

ID No. Sample Type Coal Type 24-hour pH Total Hg, μg/g 

03-006 Fly ash Eastern bituminous 6.78 0.194 

03-007 Fly ash Eastern bituminous 5.52 0.141 

04-003 Fly ash Eastern bituminous 8.54 0.685 

05-018 Fly ash Eastern bituminous 8.49 0.123 
77 

 Table 5-60. Microbiological Experiment 7 Eh and pH Results 

Anaerobic Aerobic 

ID No. Eh, mV pH ID No. Eh, mV pH 

03-006 209.0 6.98 03-006 98.3 8.87 

03-006 177.3 7.00 03-006 196 8.78 

03-006 167.7 6.87 03-006 83.8 8.70 

03-007 207.5 6.71 03-007 126 8.64 

03-007 178.3 6.64 03-007 195 8.72 

03-007 163.5 6.69 03-007 103 8.65 

04-003 95.3 6.95 04-003 156 8.77 

04-003 51.4 8.49 04-003 119 8.60 

04-003 62.3 8.49 04-003 98.5 8.61 

05-018 14.2 7.91 05-018 149 8.60 

05-018 11.5 7.86 05-018 97.0 8.63 

05-018 2.4 8.06 05-018 116 8.54 

Table 5-61. Vapor-Phase Mercury Release Results, pg/g/day, Experiment 7 

Anaerobic Aerobic 

ID No. Elemental Mercury Organomercury ID No. Elemental Mercury Organomercury 

03-006 0.130 0.164 03-006 17.9 1.91 

03-006 0.255 0.095 03-006 5.36 0.524 

03-006 0.178 0.075 03-006 6.08 0.752 

03-007 0.253 0.050 03-007 5.89 0.206 

03-007 6.17 0.104 03-007 1.11 0.215 

03-007 0.388 0.180 03-007 13.6 1.51 

04-003 0.068 0.046 04-003 15.6 0.035 

04-003 0.249 0.057 04-003 4.17 0.085 

04-003 0.285 0.039 04-003 10.3 0.174 

05-018 12.1 0.763 05-018 17.7 1.07 

05-018 0.797 0.120 05-018 21.3 0.717 

05-018 1.74 0.212 05-018 34.9 3.24 

elevated. Under anaerobic conditions, concentrations of chromium, nickel, and selenium were 

elevated. Under both conditions, concentrations of cadmium remained about the same. It could 

be hypothesized that since under aerobic conditions pH values were elevated, simple pH control 

of conditions would explain the leachate concentrations. However, the slightly depressed 

concentrations of cadmium in the aerobic experiments make that unlikely. Cadmium solubility 

over the pH range 6–9 would be expected to be much like that of lead and it was not. It is likely 

that in these experiments it was the differences in microbial and fungal populations that exerted a 

major influence in the final solution concentrations of trace elements. 

 Summaries of vapor-phase release information generated in all experiments in this subtask 

are included in Tables 5-63 for fly ash samples and 5-64 for FGD–SDA and wet FGD filtercake. 
78 

Table 5-62. Microbiologically Leached Total Trace Element Results, μg/L, Experiment 7 

Anaerobic Aerobic 

ID No. As Cd Cr Pb Hg Ni Se pH ID No. As Cd Cr Pb Hg 03-006 644 3.40 6.8 <2 0.134 128 608 6.98 03-006 2190 2.42 3.4 59.8 NT 03-006 663 3.37 6.8 <2 <0.01 122 617 7.00 03-006 2310 2.53 3.1 15.8 0.120 03-006 638 3.68 7.2 <2 <0.01 122 607 6.87 03-006 2160 2.25 <2 6.6 0.023 03-007 398 4.55 6.6 <2 <0.01 144 585 6.71 03-007 2010 2.67 <2 4.1 0.025 03-007 419 4.34 6.4 <2 <0.01 125 616 6.64 03-007 1320 3.13 3.5 8.4 <0.01 03-007 421 4.50 6.4 <2 0.247 125 602 6.69 03-007 1820 2.61 3.6 3.8 0.079 04-003 438 2.32 8.8 <2 0.009 111 655 6.95 04-003 1300 1.78 5.3 3.5 0.172 04-003 569 2.33 12.7 <2 <0.01 160 793 8.49 04-003 1170 1.70 3.1 3.2 0.157 04-003 596 2.38 12.9 <2 <0.01 160 823 8.49 04-003 1320 1.81 7.1 2.2 0.356 05-018 785 11.6 11.3 <2 NT 270 753 7.91 05-018 1290 7.96 4.1 5.1 0.191 05-018 726 10.9 10.4 <2 NT 249 723 7.86 05-018 1520 8.01 5.3 9.8 0.124 05-018 772 10.8 13.8 <2 NT 278 725 8.06 05-018 1370 8.51 4.0 3.3 0.164  Table 5-63. Summary of Vapor-Phase Mercury Releases from Microbiologically Mediated  Experiments on Fly Ash Samples 

 Vapor-Phase Hg Releases, pg/g/day  Anaerobic AerobExperiment No. ID No. Sample Type Coal Type 

Total Hg, 

μg/g 

Elemental 

Hg Organo Hg 

Elemental 

Hg O

2 01-002 FA Bituminous 0.785 0.1 – 0.24 0.008 – 

0.009 

0.09 – 1.1 

3 03-060 FA + AC Subtuminous 0.689 0.03 – 0.09 0.002 – 

0.008 

0.65 – 1.7 

4 03-079 FA Lignite 0.160 0.56 – 1.06 1.00 – 1.34 2.26 – 3.96 04 04-043 FA Lignite 0.287 0.26 – 0.44 0.12 – 0.22 0.08 – 9.30 05* 04-035 FA Lignite 0.194 0.03 – 0.04 0.03 – 0.14 0.15 – 0.20 05 04-036 FA + AC Lignite 0.41 0.03 – 0.52 0.02 – 0.14 0.26 – 0.45 07 03-006 FA Bituminous 0.685 0.13 – 0.25 0.07 – 0.16 5.36 – 17.9 07 03-007 FA Bituminous 0.123 0.25 – 6.17 0.05 – 0.18 1.11 – 13.6 07 04-003 FA Bituminous 0.234 0.07 – 0.28 0.04 – 0.06 4.17 – 15.6 07 05-018 FA Bituminous 1.86 0.80 – 12.1 0.12 – 0.76 17.7 – 34.9 0

 * Shading indicates paired samples.
79 

 Key observations made based on the results of these experiments are as follows: 

• Analysis of mercury was hindered by high analytical blanks and generation of hydrogen 

sulfide from high-sulfur samples that contaminated the analytical traps. 

• Maintenance of neutral pH and associated microbial growth could not be achieved for 

samples with an initially high pH. 

• Fungi was present in some samples under aerobic conditions and, when fungi was 

noted, the vapor-phase mercury releases were higher than in replicate sample flasks 

where no fungi was evident. 

• Aerobic conditions resulted in increased vapor-phase mercury releases for both 

elemental and organomercury for all samples evaluated. 

• The FGD–SDA and wet FGD filtercake exhibited significantly higher vapor-phase 

mercury release rates than the fly ash samples evaluated, and the FGD–SDA sample 

evaluated had the highest release rate of vapor-phase mercury. 

• The formation of organomercury compounds was evident in all of the microbiologically 

mediated experiments. It was observed, however, that organomercury formation appears 

to be directly related to the amount of fungi present in the flasks at the end of the 

experiments. 

• The mercury released from the CCB slurry was generally higher in the samples fed with 

glucose versus starved samples. The final experiments only included “fed” systems. 

 Sulfate-reducing bacteria in sulfur-rich samples such as FGD material tended to form large 

amounts of hydrogen sulfide in the anaerobic flasks. This hydrogen sulfide production required 

putting traps on the flasks in order to keep the hydrogen sulfide and its odor out of the lab. The 

Table 5-64. Summary of Vapor-Phase Mercury Releases from Microbiologically Mediated 

Experiments on FGD–SDA and Wet FGD Filtercake Samples 

 Vapor-Phase Releases, pg/g/day 

 Anaerobic Aerobic 

Experiment 

No. ID No. 

Sample 

Type Coal Type 

Total 

Hg, 

μg/g 

Total 

Hg 

Organo 

Hg 

Total 

Hg 

Organo 

Hg 

1 99-188 FGD–SDA Subbituminous 0.131 31.5 – 

43.5 

NT 1090 – 

2110 

NT 

4 03-082 Wet FGD 

Filtercake 

Bituminous 0.218 0.14 – 

2.54 

0.52 – 

20.4 

97.2 – 

130 

18 – 22

51 03-082 Wet FGD 

Filtercake 

Bituminous 0.218 1.54 NT 4.64 – 

9.69 

0.94 – 

1.62 1

 Microbes were not added. 
80 

hydrogen sulfide also made analyses impossible because of the formation of colloidal sulfur soon 

after the samples were harvested. Additionally, hydrogen sulfide collected in the CarbotrapTM 

tubes came off as elemental sulfur and precluded analyses of these traps in our normal manner. 

No solutions were developed to solve this analytical problem. 

 Highly alkaline ash samples generated from lignite have proven particularly difficult to 

maintain at near neutrality. Experiments performed in the absence of bacteria provide us with a 

neutralization capacity for acid addition, but in microbiological experiments, these neutralized 

solutions quickly rose to above pH 10.5, thus killing the bacteria. We had been using dilute 

sulfuric acid for neutralization and believe that after neutralization, a sulfate coating has 

deposited around individual particles. After bacteria were introduced, we believe that the 

bacterial action may have removed the protective sulfate coating from alkaline particles, thus 

releasing additional alkalinity. At this time, this is our only working hypothesis, and solutions 

based on this hypothesis are under investigation. 

 It is important to note that although methylation did predictably occur, the apparent rate 

and resultant concentrations of methylmercury were extremely small. Research on the issue of 

methylation of mercury and other trace elements such as selenium and arsenic are currently 

ongoing. Despite the extreme toxicity of methylated mercury species, there does not appear to be 

evidence that would lead to any need for special precautions at this time. Methylation of select 

trace elements is a phenomenon that should be expected to occur and which is known to occur in 

sites with natural sources of arsenic, mercury, and selenium. The research team’s primary 

observation was that the presence of fungi under aerobic conditions appears to be a primary 

source of methyl mercury. It was expected at the onset of these experiments that the presence of 

sulfate-reducing bacteria under anaerobic conditions would be a primary source of methylation. 

This was not the case despite the presence of sulfate-reducing bacteria in samples with high 

concentrations of sulfate. 

 The presence of these specific bacteria was determined by the strong odor of hydrogen 

sulfide in samples with high concentrations of sulfate under anaerobic conditions. The presence 

of hydrogen sulfide was significant enough that scrubbers were added to the flasks in order to 

keep the air in the lab breathable. 

5.6 Field Investigations 

 The goal of the field investigation task was to develop information to facilitate an 

understanding of how laboratory results could be used to understand the potential for releases of 

ATEs from CCBs in real-world management settings. As already stated, field concentrations of 

constituents released from CCBs by exposure to water cannot be predicted by laboratory 

leaching test results, but leaching can provide information that can be used to determine if the 

potential for mobility of one or more constituents is at a level that warrants further consideration 

prior to a material being placed in specific environmental settings or conditions. The field task 

focused on obtaining information on mercury concentrations in the air near and around CCB 

disposal facilities in order to make a preliminary determination on how to best use results from 

laboratory vapor-phase experiments to provide information valuable in an assessment of the 

potential for vapor-phase mercury release to impact atmospheric mercury loading. This task was 
81 

accomplished in two subtasks: 1) Evaluation of Vapor-Phase Mercury at CCB Disposal Sites and 

2) Small-Scale Vapor-Phase Mercury Release from Soil–Ash Mixtures. On completion of the 

first field subtask, the data were reviewed and compared with other field data, and it was agreed 

by project sponsors that instead of performing another field site investigation, it would be more 

valuable to carry out a small-scale evaluation of vapor-phase mercury release from soil–ash 

mixtures since this was an ash utilization scenario that might fall under scrutiny by regulatory 

agencies and citizen groups. 

5.6.1 Field Task 1 

 The first subtask of the field investigation task was performed at CCB management 

facilities associated with a lignite-fired power plant. The EERC contracted with UNR to perform 

the mercury flux measurements using a mercury flux chamber as reported previously by UNR 

(Engle et al., 2001; Xin et al., 2006). The field task consisted of three key activities: 1) collection 

of near-surface solid samples and water samples, where available; 2) mercury flux measurements 

taken at near-surface locations by UNR; and 3) collection of mercury samples from CCB landfill 

air at near-surface locations by the EERC. Air sampling was performed at a variety of locations 

as described in Table 4-3. 

5.6.1.1 Measurement of Mercury in Field-Collected Solid Samples 

 Water samples and replicate solid samples (EERC and UNR) were obtained for laboratory 

testing. Solid composite samples were taken of the substrate on which the mercury air sampling 

was conducted. Composite samples are described in Table 4-3. Liquid samples were collected at 

disposal ponds where possible. 

 Averages of total mercury content of samples collected by both the EERC and UNR are 

noted in Table 5-65. Results from the two entities were similar for each jointly sampled substrate 

type. The total mercury concentrations for fly ash samples were low. The wet FGD material had 

the highest total mercury. The fly ash and bottom ash/mill rejects + wet FGD material total 

mercury contents were lower than the natural grasslands (background soil) and agricultural land. 

 Fundamental characterizations of the solid samples collected in the field by the EERC are 

noted in Table 5-66 and Appendix T. The stabilized FGD material (with fly ash) had the widest 

total mercury range. Moisture content and LOI in the bottom ash/mill rejects + wet FGD material 

samples exhibited the widest range of values. The range of pH values was similar in all samples. 

5.6.1.2 Measurement of Mercury Flux by UNR 

 In situ mercury fluxes were measured under highly variable weather conditions ranging 

from bright, sunny days to cold, rainy days with strong wind. Measurements of relative humidity 

(24%–84%), solar irradiance (36–761 W/m2

), and temperature (8.6°–33.1°C) were made and 

varied widely depending on the weather conditions. Mercury flux measurements were performed 

at seven locations with varying substrates, and results are summarized in Table 5-67. 
82 

 Table 5-65. Field Sample Composites and Associated CCB Mercury Analysis 

 Results, average 

Sample Type 

Total Hg, μg/g 

EERC Results 

Total Hg, μg/g 

UNR Results (Xin and Gustin, 

2005) 

Fly Ash <0.01 <0.015 

Vegetated Fly Ash with Soil 

Cover 

NT 0.095 

Wet FGD Material + Mill Rejects 0.197 0.179 

Wet FGD Material 0.299 0.360 

Bottom Ash/Mill Rejects + Wet 

FGD Material 

0.014 NT 

Stabilized Wet FGD Material 

(with fly ash) 

0.114 0.23 

Natural Grasslands (background 

soil) 

0.050 0.05 

Agricultural Land NT 0.03 

Table 5-66. Range of Fundamental Characterization Data in Field Samples Collected by 

the EERC

Sample Type 

Total Mercury 

Content, μg/g 

Moisture 

Content, % LOI, % 

10–15-min 

pH 

Overnight 

pH 

Fly Ash <0.01 15.0 5.73 9.36 9.13 

Wet FGD Material + 

Mill Rejects 

0.188–0.207 19.3–21.3 2.18–3.31 8.62–8.68 8.51–8.53 

Wet FGD Material 0.299 23.3 2.49 8.55 8.27 

Stabilized Wet FGD 

Material (with fly 

ash) 

0.011–0.250 10.1–23.5 2.68–3.68 8.72–10.33 8.63–10.81 

Bottom Ash/Mill 

Rejects + Wet 

FGD Material 

<0.01–0.044 7.02–28.8 1.99–13.0 8.77–9.78 9.29–10.33 

Natural Grasslands 

(background soil) 

0.050 12.6 6.88 8.57 8.40 

 Mercury flux was measured from eleven areas at the site. Five fly ash-sampling locations 

with low mercury emission fluxes (from 0.0 to 1.8 ng/m2/hr) were measured, while two fly ash 

sites had higher emissions (4.5 ± 3.3 and 4.9 ± 2.5 ng/m2/hr). For two other sites, the mean flux 

indicated deposition of atmospheric mercury to the fly ash during the day. 

 Mercury flux was also measured from three sites on a vegetated fly ash substrate. The fly 

ash was covered with a 2’ clay cap and a 3’ vegetated soil layer. Two of the measurement sites 

exhibited low mean mercury emission rates (0.9 and 1.3 ng/m2

/hr), and one site had an 
83 

Table 5-67. Summary of Mercury Fluxes Measured from Landfill Facilities (after Xin 

and Gustin, 2005)

Substrate Type 

Number of Measurements on 

Substrate Surface 

Range of Flux 

Measurements, ng/m2/hr 

Fly Ash 97 −0.2–4.9 

Vegetated Fly Ash with Soil Cover 9 0.9–33.4 

Wet FGD Material + Mill Rejects 12 6.9–15.9 

Wet FGD Material 61 0.3–2.5 

Stabilized Wet FGD Material (with 

fly ash) 

61 0.7–22.2 

Natural Grasslands (background 

soil) 

9 −0.1–0.3 

Agricultural Land 9 0.0–2.3 

exceptionally high mercury mean emission rate (33.3 ng/m2

/hr). The high flux rate value was not 

used in further calculations because the sampling location was close to an active road and 

potentially had contaminated road dust or other road-related deposits to the soil surface. 

 For the wet FGD material substrate, which was disposed of in an ash pond, mercury 

emission flux was low. The mean daytime mercury flux was 1.3 ± 0.8 ng/m2/hr and the mean 

nighttime mercury flux was 0.3 ± 0.3 ng/m2/hr. The low emission for the saturated FGD 

material, as compared to that for wet but not saturated material, is similar to that reported for 

soils. Soils that are saturated have been shown to have low Hg emissions, but as soils dry, 

emissions increase (Gustin and Stamenkaric, 2005). Mercury emission rates were highest from 

the wet FGD materials. 

 For the stabilized wet FGD material (with fly ash) substrate, mercury flux varied 

significantly among measurement sites. Low mean mercury emission fluxes were measured at 

three sites (0.7–4.8 ng/m2

/hr), while higher mercury emission values were observed at two sites 

(10.9–22.2 ng/m2

/hr). The average daytime mercury flux was 11.5 ± 12.7 ng/m2/hr, and the 

average nighttime mercury flux was 10.9 ± 7.2 ng/m2/hr. The high variability of the data may be 

explained by the inhomogeneity of the wet FGD material and fly ash mixture within the disposal 

site. No correlation between mercury flux and light was observed for this substrate. The windy 

conditions when flux measurements were made on this substrate could also have affected the 

mercury flux (Gustin et al., 1997). 

 Mercury emissions were also measured for two types of soils in the surrounding area: a 

natural soil not obviously impacted by agriculture and a field. Mean flux ranged from 

−1–2.3 ng/m2

/hr during the day. 

 Observations can be summarized as follows: 

• Wet FGD material (with fly ash) exhibited the highest release. 
84 

• Fly ash substrates exhibited very low mercury emissions, with the exception of one 

potentially contaminated site. 

• Fly ash, vegetated fly ash with soil cover, and wet FGD material exhibited low mercury 

emissions similar to the background natural grasslands and agricultural land. 

• No strong correlation was observed between mercury flux and total mercury 

concentration for the substrates evaluated. 

 The flux measurements were used to calculate an annual mercury release for each 

substrate, and those calculated releases are noted in Table 5-68 (Xin and Gustin, 2005). Based on 

calculations for this field site, about 20.6 g Hg/yr would be emitted from the five sites evaluated. 

For the same area of natural grassland, 0.4 g Hg/yr would be emitted, and 5.5 g Hg/yr would be 

emitted from the agricultural land. 

 Data from this work were compared with data collected from a CCB landfill facility in the 

eastern United States (Gustin and Ladwig, 2004) and a CCB landfill located in the Great Lakes 

area of the United States. The eastern site was a bituminous fly ash landfill visited in October 

2002 and the Great Lakes site was a blended bituminous–subbituminous fly ash landfill visited in 

October 2003. The comparison data are shown in Table 5-69. Assuming a disposal area of 

100,000 m2

 for all substrates at all disposal sites, annual mercury emissions were calculated. 

These are also included in Table 5-69. 

 The highest calculated mercury releases were noted for the lignite-based stabilized wet 

FGD material (with fly ash) and the wet FGD material + mill rejects. The lignite-derived barren 

fly ash had the highest mercury flux compared to bituminous and blended bituminous–

subbituminous fly ash. Vegetated fly ash from the eastern United States and Great Lakes area 

acted as a mercury sink (mercury flux <0), whereas vegetated fly ash at the lignite site indicated 

 Table 5-68. Summary of Scaling of Emissions Using Field Site Data (Xin and Gustin, 2005)

Sample Type Area1, m

2

Mean Flux, 

ng/m2/hr Total Annual Flux, g/yr 

Barren Fly Ash 141,642 1.1 1.4 

Vegetated Fly Ash 56,657 1.1 0.5 

Stabilized Wet FGD 141,642 11.2 13.9 

Unstabilized Wet FGD 141,642 0.8 1.0 

Wet FGD + Mill Rejects 40,469 10.9 3.9 

TOTAL 522,050 - 20.6 

 

Natural Grassland 

(background soil) 

522,050 0.1 0.4 

Agricultural Land 522,050 1.2 5.5 

1

 Areas was estimated according to the field site landfill map. 
85 

Table 5-69. Comparison of Scaling of Hg Flux Using In Situ Data from Three Landfill Sites 

(Field site examined in this report, one site in Eastern United States, and one site in the 

Great Lakes area of the United States. Area used for scaling is 100,000 m2

 for each 

substrate. Mean flux was the average flux obtained from daytime and nighttime flux [Xin 

and Gustin, 2005]) 

Location Coal Type Sample Type 

Mean Flux, 

ng/m2

/hr 

Total Annual 

Flux, g/yr 

Barren fly ash 1.1 0.9 

Vegetated fly ash 1.1 0.9 

Stabilized wet FGD 11.2 9.8 

Unstabilized wet FGD 0.8 0.7 

Wet FGD + mill rejects 10.9 9.5 

Natural grassland 0.1 0.1 

Field Site 

 Described in 

 This Report 

Lignite 

Agricultural land 1.2 1.1 

Barren fly ash −0.2 −0.2 

Soil-covered fly ash −9.5 −8.3 

Eastern United 

 States 

Bituminous 

Vegetated fly ash −0.2 −0.2 

Barren fly ash 0.9 0.8 

Vegetated fly ash −0.1 −0.1 

Great Lakes Area 

 in United States 

Blended 

bituminous and 

subbituminous Soil 0.5 0.5 

a release of mercury. Xin et al. (2006) provides a detailed discussion of data collected in the 

eatstern United States and the Great Lakes region. 

5.6.1.3 Measurement of Mercury in CCB Landfill Air by the EERC 

 Using the method described in the experimental section, sampling was performed at 

several locations at the CCB landfill site. Measurements were taken at locations near the UNR 

mercury flux measurement locations when possible. Results generated by the EERC at storage 

sites for elemental mercury captured on gold traps and organomercury captured on Supelco 

CarbotrapTM-containing tubes are outlined in Table 5-70. The results are reported as ng/m3, 

which refers to the amount of mercury captured on traps while a determined amount of CCB 

landfill air was drawn through the tubes. 

 The measured CCB landfill air mercury values were low and generally comparable to air 

measurements made at locations in the natural grasslands, which served as an undisturbed 

background site. The highest elemental mercury concentrations were measured near the wet 

FGD material + mill rejects. Most of the other elemental mercury air measurements were similar. 

 The measured organomercury concentrations, however, were all very low, with the 

stabilized wet FGD material (with fly ash) sampling location yielding the highest reading. 
86 

Table 5-70. Average CCB Landfill Mercury Readings and Standard Deviation, ng/m3

 (field 

blanks were subtracted) 

Substrate Type 

Elemental 

Mercury n Organomercury n 

Calculated 

Total Mercury 

Fly Ash 1.021 ± 0.238 4 0.052 ± 0.038 2 1.073 

Vegetated Fly Ash with Soil 

Cover 

0.616 ± 0.277 4 0.019 ± 0.026 2 0.635 

Wet FGD Material + Mill 

Rejects 

1.459 ± 0.995 4 0.006 ± 0.002 2 1.465 

Wet FGD Material 0.954 ± 0.413 4 0.045 ± 0.042 2 0.999 

Bottom Ash/Mill Rejects + Wet 

FGD Material 

0.541 ± 0.193 4 0.023 ± 0.011 2 0.564 

Stabilized Wet FGD Material 

(with fly ash) 

0.849 ± 0.378 4 0.354 ± 0.476 2 1.203 

Natural Grasslands (background 

soil) 

0.640 ± 0.270 4 0.017 ± 0.004 2 0.657 

 In Table 5-70, a calculated total mercury for air at each location is included. Using this 

value, the measurements can be listed from highest to lowest: 

 Wet FGD material + mill rejects 

 > Stabilized wet FGD material (with fly ash) 

 > Fly ash 

 > Wet FGD material 

 > Natural grasslands (background soil) 

 > Vegetated fly ash with soil cover 

 > Bottom ash/mill rejects + wet FGD material (sample not evaluated by UNR) 

 In comparison, the mercury flux measurements performed by UNR resulted in the 

following indication of high to low mercury associations by substrate: 

 Wet FGD material + mill rejects 

 > Stabilized wet FGD material (with fly ash) 

 > Fly ash 

 > Agricultural land (sample not evaluated by EERC) 

 = Wet FGD material 

 > Vegetated fly ash with soil cover 

 > Natural grasslands (background soil) 
87 

5.6.2 Alternate Field Task 

The Phase 2 field investigation (alternate field task) was developed in response to project 

sponsor input on results of Field Task 1. It was agreed that a useful addition to this task would be 

to evaluate the impact of interaction between soil and CCBs on mercury release from CCBs, 

especially since CCBs are used in numerous soil applications. The interaction of greatest interest 

was that caused by inherent microbiological organisms typically found in soils. The CCB–soil 

laboratory experimental apparatus was designed to evaluate microbiologically mediated mercury 

release from CCB–soil mixtures, analogous to utilization management practices in the field. 

Elemental mercury and organomercury release measurements were evaluated. Fundamental 

characterization data of the soil used are in Appendix T. 

 The results of the elemental mercury release are shown in Table 5-71, reported in a manner 

similar to the long-term ambient-temperature release experiments for CCBs. The total mercury 

content of the CCB–soil mixtures was not measured; therefore, a calculation based on the total 

mercury content of the separate components and the mixture percentage is given in Table 5-71. 

Each sample bottle had a blank bottle measurement of elemental mercury prior to introduction of 

the CCB–soil mixture. Sorption or release of elemental mercury was determined by subtracting 

the blank value from the measurements. The calculations in the columns labeled “Cumulative % 

Elemental Hg Sorption or Release from Mix” and “Years to Release 100% Elemental Hg at 

Measured Rate” are based on the calculated mixture total mercury content. Paired samples 

(Samples 05-038 and 05-025) are highlighted; these samples are from the larger sample set of 

paired lignite fly ash samples. 

 During the duration of the experiment, the research team was unable to collect replicate 

data for two samples (Samples 05-038 and 06-014) because of apparatus difficulties that 

developed. 

 The results show that the soil–peat moss mixture (only one data point) used in this task 

sorbed elemental mercury. The CCB–soil mixtures exhibited low levels of elemental mercury 

release, with the exception of one replicate. On average, over 100,000 years of air movement 

over the CCB–soil mixtures is required to release all mercury from the system. Samples that had 

AC present released lower percentages of elemental mercury than those without AC present, 

even though the total mercury was higher in the samples with AC, especially those collected 

after the primary PCD. On average, the samples with AC present released mercury an order of 

magnitude lower percentage than the sample from a similar coal source without AC. However, as 

shown in Appendix U, the measured elemental mercury release rate was higher for the fly ash + 

AC (post-primary PCD) samples. The paired sample set provided a good comparison of a fly ash 

sample without and with AC present. 

 Organomercury results are reported in Table 5-72. No organomercury blank value 

measurements were performed since preparation of the experimental vessel (heating to >500°C) 

was expected to eliminate any organomercury from the container. Therefore, the organomercury 

collected from the soil-only bottle served as the blank for the experiment. This allowed for a 

determination of the impact of each CCB in each CCB–soil mixture. 
88 

Table 5-71. Alternative Field Task (CCB–soil) Elemental Mercury Results Summary. Positive values indic

negative values indicate sorption of elemental mercury. Duplicate bottles are represented.

 Replicate 1 ID No. Sample Type Coal Type 

Calculated 

Mixture 

Total Hg, 

μg/g 

Cumulative 

No. Days 

Cumulative 

% Elemental 

Hg Sorption 

or Release 

from Mix 

Years to 

Release 100% 

Elemental Hg 

at Measured 

Rate 

Cumula

% Eleme

Hg Sorp

or Rele

from M

04-003 Fly ash Eastern 

bituminous 

0.190 167 0.00105 43,693 0.00059

04-054 Fly ash + AC 

(post-primary 

PCD) 

Eastern 

bituminous 

3.60 167 0.000288 158,678 0.00029

04-029 Fly ash PRB 

subbituminous 

0.106 167 0.00529 8,650 0.00414 

03-060 Fly ash + AC 

(pre-primary 

PCD) 

PRB 

subbituminous 

0.426 166 −0.000195 NA – sorbing 0.00012

05-0381 Fly ash Lignite 0.0740 166 0.00266 17,075 NQ2 05-025 Fly ash + AC 

(post-primary 

PCD: high ash) 

Lignite 2.58 167 0.000205 222,968 0.00026

05-009 FGD gypsum Eastern 

bituminous 

0.0598 166 0.00181 25,189 0.00101 

06-014 Soil None 0.0666 166 NQ NQ −0.00205 

1 Shading indicates paired samples. 2 Not quantitated. 
89 

Table 5-72. Alternative Field Task (CCB–soil) Organomercury Results Summary. Results are expressed a

the soil used as blank. Positive values indicate release, and negative values indicate sorption of organomercbottles are represented.

Replicate 1 Replic

ID No. Sample Type Coal Type 

Calculated 

Mixture 

Total Hg, 

μg/g 

Cumulative 

No. Days 

Cumulative % 

Organomercury 

Sorption or 

Release from 

Mixture 

Compared to Soil

Years to Release 

100% 

Organomercury 

at Measured Rate 

Compared to Soil

Cumulative % 

Organomercury 

Sorption or 

Release from 

Mixture 

Compared to Soil

04-003 Fly ash Eastern 

bituminous 

0.190 168 0.00134 34,465 0.000977 

04-054 Fly ash + AC 

(post-primary 

PCD) 

Eastern 

bituminous 

3.60 171 −0.0000123 NA – below soil 

release 

−0.0000207 

04-029 Fly ash PRB 

subbituminous

0.106 169 −0.000531 NA – below soil 

release 

−0.000481 

03-060 Fly ash + AC 

(pre-primary 

PCD) 

PRB 

subbituminous

0.426 167 −0.000248 NA – below soil 

release 

−0.000261 

05-0381 Fly ash Lignite 0.074 168 −0.00124 NA – below soil 

release 

NQ 

05-025 Fly ash + AC 

(post-primary 

PCD: high ash) 

Lignite 2.58 172 0.0000297 1,588,470 −0.0000109 

05-009 FGD gypsum Eastern 

bituminous 

0.0598 168 −0.000418 NA – below soil 

release 

0.00358 

1 Shading indicates paired samples.
90 

 The results indicated that more organomercury was released from four of 13 replicate 

CCB–soil mixture bottles than from the soil-only bottle. All organomercury releases were low. 

Again, the samples with AC generally exhibited a lower-percentage release of mercury than 

those without AC present, although the difference was not as consistent as that observed for 

elemental mercury releases. The fly ash alone from the paired sample set released a lowerpercentage organomercury by two orders of magnitude when compared to the fly ash + AC in the 

paired set. 

 The CCB sample elemental mercury vapor profiles for this task versus long-term ambienttemperature release and microbiologically mediated vapor-phase transport task profiles are 

provided in Table 5-73. The FGD gypsum sample evaluated in this task (Sample 05-009) 

exhibited elemental mercury release whether analyzed alone or when mixed with soil. Generally, 

fly ash samples that exhibited an overall elemental mercury sorption in the long-term ambienttemperature release experiment released mercury in the alternate field task when combined with 

soil. It was hypothesized by the project team during performance of the microbiologically 

mediated mercury release experiments that carbon (either unburned or activated) would provide 

a source of food for the microbes present in the system and might promote release of mercury. 

These limited results support that hypothesis. 

5.7 Data Reduction and Interpretation 

 The standard analysis techniques used in the project indicate acceptable performance 

criteria. The repeatability of the data was within the expected ±20%, with the exception of the 

data produced in the microbiological experiments. In this case, the experiments are still a work in 

progress, with much improvement yet needed on the technique. This is nearing completion. 

Despite more variability than had been hoped for, the data still proved useful. 

 Data reduction and interpretation was performed on a task basis for the release and field 

tasks, incorporating information from the method and sample selection tasks. Data interpretation 

incorporated information from real-world ash management scenarios in an attempt to draw 

conclusions on Hg ATE releases under disposal and use scenarios. 

6.0 CONCLUSIONS AND RECOMMENDATIONS 

 This project achieved its stated objectives, and based on the results of the laboratory and 

field experiments conducted in this project, the following conclusions were drawn: 

• Results for “paired” baseline and test fly ash and FGD–SDA samples indicated that 

total mercury content was higher in the test samples. Test samples contained AC 

injected as mercury sorbent with one exception, where an EA only was injected. The 

higher total mercury content was also generally noted for all fly ash samples collected 

from systems without mercury emission controls as compared to fly ash that was 

collected from systems with mercury emission controls in place. No similar trend was 

noted for the limited nonpaired FGD–SDA samples. 
91 

Table 5-73. Overall Elemental Mercury Vapor Profiles in Noted Tasks

Long-Term AmbientTemperature Release Alternate Field Task 

ID No. Sample Type Coal Type 

Total Mercury 

Content, μg/g LOI, % CCB Only 

CCB–Soil 

Mixture 

04-003 Fly ash Eastern 

bituminous 

0.685 8.45 NT Release H

04-054 Fly ash + AC (postprimary PCD) Eastern bituminous 17.7 18.6 Sorption Release 04-029 Fly ash PRB 

subbituminous 

0.261 0.48 Sorption Release 

03-060 Fly ash + AC (preprimary PCD) PRB subbituminous 1.86 2.37 Release Sorption H

05-0381 Fly ash Lignite 0.104 0.22 Sorption Release 05-025 Fly ash + AC (postprimary PCD: high 

ash) 

Lignite 12.6 3.19 Sorption Release 

05-009 FGD gypsum Eastern 

bituminous 

0.032 1.92 Release Release 

06-014 Soil None 0.067 44.2 NT Sorption 

1 Shading indicates paired samples.
92 

• The total selenium content of “paired” baseline and test fly ash samples with postprimary PCD ACI was higher for the test samples than the baseline samples. This trend 

was not noted for “paired” samples with pre-primary PCD ACI or generally for the 

nonpaired samples. 

• Total concentrations of arsenic, cadmium, chromium, lead, and nickel were similar for 

all fly ash samples and FGD–SDA samples collected from systems with or without 

mercury emission controls in place. This was true for “paired” and nonpaired samples. 

• Direct leaching tests indicated that mercury was not readily leached from fly ash or 

FGD materials. 87% of samples leached had at least one leachate mercury concentration 

below the 0.01 μg/L analytical reporting limit. Mercury leachate concentrations did not 

correlate to total mercury concentrations. In particular, the samples with the highest 

total mercury content showed no detectable leachate mercury. These conclusions were 

consistent for both paired and nonpaired samples. 

• When exposed to ambient-temperature air in laboratory experiments, fly ash samples 

either released or sorbed small amounts of mercury. Samples containing unburned 

carbon or AC tended to sorb mercury in ambient-temperature vapor-phase experiments. 

For fly ash samples that release mercury, the rate of release generally decreased with 

time. For those that sorbed mercury, the rate of sorption was generally increased over 

the duration of the experiments. All wet FGD material, including FGD gypsum released 

mercury in ambient-temperature laboratory experiments. When releases were noted, 

they were extremely low, both in total released over extended laboratory tests and in 

rate released. Laboratory data indicated that the potential for ambient-temperature 

vapor-phase mercury releases from CCBs is unlikely to impact atmospheric mercury 

loading. 

• Mercury was not released to the vapor-phase at temperatures below 250°C in elevatedtemperature experiments. For some samples, the presence of AC with fly ash increased 

the temperature at which mercury was released when exposed to elevated temperature, 

but these samples were too limited in number to draw a final conclusion on the effect of 

AC on the initial release temperature for fly ash + AC. For most fly ash samples with 

and without AC present, all mercury was released from the sample before the sample 

reached 750°C. Interferences from sulfur compounds precluded the use of the method 

developed for FGD materials. 

• Under microbiologically mediated conditions, elemental and organomercury were 

released both to the vapor phase and the leachate. While the levels of elemental and 

organomercury were low in both leachate and vapor, more elemental mercury was 

released. Fly ash samples with high pH values did not support microbial growth because 

the buffering capacity of the samples was too great. Samples of FGD material released 

hydrogen sulfide so mercury releases could not be quantitated. Very low amounts of 

elemental and organomercury releases were measured from soil–CCB mixtures in 

simulated field experiments. The results were consistent between the two experiments. 
93 

• Field experiments evaluated vapor-phase releases at a CCB disposal site. Results 

indicated low-level vapor-phase mercury releases, as was generally noted in laboratory 

experiments for lignite fly ash samples. Releases from FGD materials were noted both 

in laboratory and field measurements. 

• Laboratory methods were developed to evaluate the potential for mercury releases 

under several release mechanisms. 

 Based on the results of this project, the following recommendations were made: 

• Further work is needed on fly ash + noncarbon sorbents, fly ash + EAs, and fly ash + 

carbon and noncarbon sorbents with EAs. 

• Further investigations are required to better quantitate mercury releases from FGD 

materials and understand the mechanisms of release. 

• Highly alkaline fly ash samples with or without sorbent or additives do not need to be 

subjected to microbiologically mediated release experiments. Future work could include 

samples of alkaline fly ash mixed with other CCBs such as FGD material that might 

provide adequate neutralization to support microbial growth. 

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APPENDIX A 

SAMPLE IDENTIFICATION FORM 
SAMPLE IDENTIFICATION FORM 

Mercury and Air Toxic Element Impacts of Coal Combustion Byproduct 

Disposal and Utilization 

Company: 

Station: Unit: 

Contact Name (to relay data): 

Date Sample Collected: 

SYSTEM INFORMATION 

BURNER TYPE 

Pulverized Coal-Fired 

Cyclone 

Stoker 

Fluidized-bed combustion (FBC) 

Low-NOx Burners 

PARTICULATE COLLECTION 

Fabric Filter (FF) 

Electrostatic Precipitator (ESP) Cold Side 

ESP Hot Side 

ESP/Mechanical 

FF/Mechanical 

Other: 

SO2 CONTROL 

None 

Wet Flue Gas Desulfurization (FGD) (calcium based) 

Lime 

Limestone sorbents 

Forced oxidation 

Natural or in situ oxidation 

Dry FGD (calcium based) 

Spray Dryer Atomizer 

Wet FGD (alkali based) 

Dry FGD (alkali based) 

Other: 

AMMONIA-BASED SYSTEM 

None 

Ammonia Injection 

Selective Catalytic Reduction 

Selective Noncatalytic Reduction 
MERCURY CONTROL 

None 

Carbon Injection Injection Rate: 

Noncarbon Sorbent Injection Injection Rate: 

Modified FGD 

Fine Particulate Control 

Fly Ash from Carbon Removal Technologies 

Other: 

SAMPLE INFORMATION 

FUEL TYPE 

Bituminous 

Subbituminous 

Lignite 

Bituminous–Subbituminous Blend: % Bituminous/ % Subbituminous 

Subbituminous–Lignite Blend: % Subbituminous/ % Lignite 

Oil 

Other 

SAMPLE TYPE(S) 

Fly Ash 

FGD 

Blend: % / % 

Filtrate 

Other: 

COLLECTION POINT(S) 

FF 

ESP Field 

Specify: 

ESP Hopper 

Specify: 

Silo 

Pond/Landfill 

Other: 

OTHER INFORMATION 

 
Project ID Sample Type Collection Point Other Description 

03-321 EXAMPLE 

Fly Ash ESP Row 2 Composite 03/21/03–04

Carbon Injection 5 lb/M

Return this form and samples to: lheebink@undeerc.org Loreal Heebink Phone: (701) 777-5116 Energy & Environmental Research Center Fax: (701) 777-5181 15 N 23rd Street Grand Forks, ND 58203 
APPENDIX B 

DRAFT STANDARD METHOD FOR SYNTHETIC 

GROUNDWATER LEACHING PROCEDURE 
APPENDIX A 

DRAFT ASTM STANDARD METHOD FOR 

SYNTHETIC GROUNDWATER LEACHING 

PROCEDURE
DRAFT

1 

DRAFT ASTM STANDARD METHOD FOR 

SYNTHETIC GROUNDWATER LEACHING PROCEDURE 

1. Scope 

1.1 This method determines the leachability of constituents in wastes, products, or materials 

using a leaching solution designed to simulate leachate anticipated in field conditions. 

The method allows for prediction of changes in leachability brought about as a result of 

the formation of secondary hydrated phases and new minerals through interaction of the 

waste and water over extended periods of time. 

1.2 his method consists of the agitation of waste and a synthetic groundwater solution over 

an extended period of time (greater than 60 days) with sampling at regular intervals. 

1.3 This method allows a comparison of maximum leachate concentration with actual 

concentrations of leachate at time intervals of from 18 hours to 2 months or greater. The 

method allows for determination of mass of analyte mobilized based on a leachate 

concentration and percent of total element leached and provides information to estimate 

leachate concentration trends with respect to time. 

1.4 This method may involve hazardous materials, operations, and equipment. This standard 

does not purport to address all of the safety problems associated with its use. It is the 

responsibility of whoever uses this method to consult and establish appropriate safety 

and health practices and determine the applicability of regulatory limitations prior to use. 

2. Applicable Documents 

2.1 American Society for Testing and Materials (ASTM) Standards: 

D1129 Definitions of Terms Relating to Water 

D1193 Specification for Reagent Water 

D3987 Shake Extraction of Solid Waste with Water 

D2216 Method for Laboratory Determination of Moisture Content of Soils 

2.2Toxicity Characteristic Leaching Procedure (TCLP) EPA Method 1311 

 

3. Definitions 

3.1 For definitions of terms in this test method, see Definitions D1129. 

3.2 Ettringite: Ettringite is a mineral having the nominal composition Ca6Al2(SO4)3(OH)12 

·26H2O. Ettringite is also the family name for a series of related compounds as is the 

case for many mineral families. Ettringite has characteristic structural features that are 

fairly unique. The structure comprises of calcium aluminate columns 

{Ca6Al2(OH)1224H2O}6+ with the channels between these columns containing the other 

components, which include an oxyanion such as sulfate with hydroxide and water 

{(SO4)2-4 (OH)0-4 (H2O)0-6}6-. Ettringite is unique in that several elements that exist as 

oxyanions can substitute for the sulfate in the structure. These elements include but are 

not limited to arsenic, boron, chromium, molybdenum, selenium, and vanadium. 

Ettringite is known to form in the hydration of low-rank coal conversion solid residues 
DRAFT

2 

(CCSRs) and in CCSRs from advanced coal combustion processes such as fluidized-bed 

combustion (FBC) and limestone injection modified burner (LIMB). 

3.3 Synthetic Groundwater: Synthetic groundwater as used in this application refers to a 

solution prepared in the laboratory containing the major geochemical parameters that 

would be found in water likely to contact the disposed CCSR. In the case of rainwater 

contact, this solution would be Type IV water, while with groundwater, a typical 

solution might contain calcium, magnesium, sodium, sulfate, and bicarbonate. 

Groundwater collected at the site of disposal could also be used, although if that were 

the case, corrections would have to be made for concentrations of trace elements already 

present in the water. It has been found with most CCSRs that it is the CCSR that 

regulates the equilibrium concentrations of major constituents in a synthetic groundwater 

leaching procedure; thus the inclusion of major geochemical constituents of actual 

groundwater may be unnecessary in many cases. 

4. Significance and Use 

4.1 This test is intended as a means for determining the mass of analyte readily mobilized by 

leaching with groundwater and also provides a means of determining the trend of 

leachate concentration change, if applicable. This test is intended for use with CCSRs 

and other materials formed under conditions of high temperature. The long-term nature 

of the test allows the determination of changes in concentrations of leached constituents 

as materials react with water to form secondary hydrated phases and other materials not 

present in the original material. 

4.2 This test method is not intended to provide an accurate means of determining actual 

leachate concentrations under field conditions. The test does provide information about 

leaching under field conditions, however, and is useful in predicting the mobility of 

leachable constituents of CCSRs. The information provided from this test is an 

estimation of the mass of analyte that can be solubilized and trend of concentration 

change with respect to time. It should be noted that not all analytes will increase in 

concentration to an equilibrium level. Numerous elements, especially those trace 

elements that exist as oxyanions in aqueous solution, can exhibit a decrease in solution 

concentration after an initial and normally rapid increase in concentration. Additionally, 

major constituents can change solution concentration in a manner that would not be 

predicted on the basis of solubility calculations based on common mineral types, 

especially in CCSRs that form ettringite. 

4.3 Since CCSRs are produced under conditions of high temperature, reactions with water 

during leaching can be expected. If these reactions produce ettringite, the concentrations 

of analytes present in solution as oxyanions can be expected to decrease with respect to 

time as ettringite forms. Other mineral formation can be expected to control leachate 

concentrations of additional analytes in ways not expected from simple solubility 

calculations based on the composition of ash before leaching. Additionally, the 

formation of secondary hydrated phases can be expected to affect the concentrations of 

major components. 
DRAFT

3 

5. Apparatus 

5.1 For a complete description of the apparatus, see ASTM Standard Test Method for Shake 

Extraction of Solid Waste with Water. Any apparatus that can provide conditions of endover-end agitation at 30 plus or minus 2 rpm as specified in the protocol for the TCLP 

can be used in this procedure. 

6. Reagents 

6.1 Purity of Reagents – Reagent-grade chemicals can be used, provided they do not contain 

appreciable amounts of elements to be determined in the extraction test. Reagents must 

be of sufficient purity so they do not interfere with the accuracy of the test or introduce 

bias in the results of analyses of leachates. 

6.2 Purity of Water – Unless otherwise indicated, references to water shall be understood to 

mean Type IV reagent water at 18° to 27°C (Specification D1193). The method by 

which the Type IV water is prepared (distillation, ion exchange, reverse osmosis, etc.) 

should remain constant throughout the test. 

6.3 Synthetic Groundwater – Synthetic groundwater is a leaching solution containing the 

major geochemical parameters important to groundwater likely to contact disposed 

CCSRs. As previously stated, in the case of CCSRs disposed above the water table and 

where the likely water to contact the disposed materials is rainwater, Type IV water can 

be used as the leaching solution. Where the water likely to contact disposed material is 

highly mineralized, either a sample of the water itself or a synthetic mixture prepared in 

the lab will be used. A typical North Dakota synthetic groundwater can be prepared by 

dissolving 0.50 grams of sodium sulfate and 1.00 grams of sodium bicarbonate in one 

liter of Type IV water. The analysis of this solution is as follows: 

Na 436 mg/L 

SO4 338 mg/L 

HCO3 726 mg/L 

pH 8.3–8.7 

This sodium sulfate bicarbonate buffered water is typical for central and western North Dakota. 

Used for leaching low-rank coal ash, calcium was omitted since the ash itself ultimately 

determined the final calcium concentration. 

Other formulas for synthetic groundwater can be prepared as needed for site-specific 

conditions. Care is required when preparing formulations containing calcium and magnesium 

that carbonates not be allowed to precipitate. This can be overcome by adding the reagents in 

the proper order, being certain that all carbonate is buffered to bicarbonate before adding the 

calcium and magnesium. Since sulfuric acid is used for sulfate and acid buffering, having 

excess sulfuric acid acidity will ensure this. A lotus spreadsheet is available for the calculations 

necessary to select reagents for synthetic groundwater formulations, but with the limited 

components, the calculations can also be easily carried out manually. 
DRAFT

4 

7. Sampling 

8. Sample Preparation 

8.1 For sample preparation, see D3987 Standard Test Method for Shake Extraction of Solid 

Waste with Water. 

9. Procedure 

 The laboratory protocol is similar to the U.S. Environmental Protection Agency (EPA) TCLP 

and ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water. The 

primary difference is in the selection and preparation of the extraction fluid and the extension of test 

equilibration time over the prescribed 18-hour period. The long-term leaching aspect of this test is 

especially important since CCSRs can form secondary hydrated phases upon contact with water that 

can have a profound impact on leachate concentration of trace elements, especially elements that tend 

to exist as oxyanions in solution. The formation of secondary hydrated phases is known to take time, 

depending on the source of reactants in the leaching system. Time for complete formation of 

secondary hydrated phases can be from days to months. The test is not intended to carry the leaching 

to complete equilibrium but rather to extend the leaching time long enough for prediction of leachate 

concentration trends. For specifics related to the test, see D3987 Standard Test Method for Shake 

Extraction of Solid Waste with Water, or EPA Method 1311 TCLP, Federal Register, Vol 55, No. 

126, June 29, 1990. 

9.1 Record the physical description of the sample to be tested including particle size as 

known. 

9.2 Solids Content – Determine the solids content of the sample as described in D3987 

Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.2.1 

through 9.2.4. 

9.3 Shake Procedure – Prepare the apparatus and begin the test as described in D3987 

Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.4 

through 9.7, except that multiple shake test containers are prepared for each sample, the 

number depending on the duration of long-term leaching. Leaching solution shall be 

prepared as described in the following section. Long-term leaching intervals for this 

procedure are 18 hours, 1 week, 1 month, and 2 months. Longer times can be used if 

desired, although trends are usually identified within the 60-day duration of this longterm leaching procedure. An alternative to the use of 2 liters of leaching solution 

involves the use of 225-mL polysulfone bottles. To each bottle, 10 grams (dry weight) of 

ash is added along with 200 mL of leaching solution. Multiple bottles prepared in this 

manner provide at least 150 mL of leachate and allow for the simultaneous extraction of 

a large number of samples with minimal space and equipment. It has been found that the 

standard equipment used for TCLP leaching will generally hold four of the polysulfone 

containers in the same position usually reserved for one 2-liter container. 

9.4 Preparation of Leaching Solution: Leaching solution shall be prepared as recommended 

by an evaluation of field conditions. Where material disposed in a monofill is above the 

water table, the leaching solution shall be Type IV water (D1193 Specification for 

Reagent Water). Where the disposed material will likely be contacted by groundwater, 
DRAFT

5 

either a sample of groundwater from the site or a synthetic groundwater shall be used for 

leaching. The synthetic groundwater if prepared in the lab shall contain all of the 

primary mineralization parameters as determined from an analysis of groundwater from 

the site or from an evaluation of data from analysis reports of water representative of the 

area of disposal. 

9.5 Long-Term Leaching Sampling B Long-term samples are taken from containers prepared 

for the shake test in an identical manner to the specimen for the 18-hour sampling 

period. These containers are sampled at the end of 1 week, 1 month, and 2 months. 

Longer sampling intervals can be added as required. A convenient method for doing this 

procedure is to prepare the samples at time intervals so that all of the samples are 

finished at the same time. For example, one sample is prepared, a second is prepared 1 

month later, a third sample 1 month later, and a final sample 18 hours before the other 

samples are due to be terminated. This saves considerable lab time and expedites the 

entire procedure. 

9.6 Sampling of Leachate B Leachate is sampled for analysis as specified in D3987 Standard 

Test Method for Shake Extraction of Solid Waste with Water, Section 9.8. 

9.7 Analysis 

9.7.1 Selection of Analytes to Be Included in the Report. Analytes include all elements 

present in the ash in high enough concentrations to be problematic in disposal. 

These can be determined through screening procedures such as proton-induced 

x-ray emission (PIXE), instrumental neutron activation analysis (INAA), or 

plasma emission such as inductively coupled argon plasma (ICAP) spectroscopy 

or ICAP–mass spectrometry. Analytes for ash screening generally include the 

eight Resource Conservation and Recovery Act (RCRA) elements for regulatory 

purposes. 

9.7.2 Determination of Total Concentration of Select Analytes. Analytes selected on 

the basis of screening (9.6.1) are determined on a bulk sample prepared by 

digestion of sample in a microwave heated-sealed Teflon bomb. Analyses can be 

performed according to methods for trace analyses in SW846. 

9.7.3 Determination of Analyte Concentrations in Leachates. Concentrations of 

analytes in leachates shall be determined using methods as described in SW846 

or by approved analytical techniques using EPA or other approved techniques. 

All data shall be validated using good laboratory practice and approved quality 

assurance/quality control (QA/QC) procedures. 

10. Calculation 

10.1 Calculate the solids content as specified in D3987 Standard Test Method for Shake 

Extraction of Solid Waste with Water, Section 10.1. 
DRAFT

6 

10.2 Calculation of maximum analyte concentration is determined by dividing the total mass 

of analyte in a sample by the volume of liquid used for leaching. C = M/V where 

C = Concentration of analyte 

M = Mass of sample leached 

V = Volume of leaching solution used 

For this procedure the M:V ratio should be 1:20 as specified in the leaching protocol. 

11. Report 

11.1 The report shall include the following: 

11.1.1 Source of CCSR, date of sampling, and preservation method used for leachates. 

11.1.2 Description of CCSR including coal source, combustion technique, and method 

of sample collection (electrostatic precipitator, baghouse, etc.) 

11.1.3 Solids content (see Method D2216) 

11.1.4 A table of maximum analyte concentrations as determined by the method 

described in Section 10.2. (bulk chemical analysis) 

11.1.5 A table of analyte concentrations as determined from analysis of 18-hour, 1-

week, 1-month, 2-month, and any additional extended time intervals selected. 

12. Precision and Bias 

12.1 No information is presently available on the precision and accuracy or bias of this 

standard practice. It is recommended that standard QA/QC procedures such as analysis 

of duplicate samples and spiking of analyte be used for verification. 

12.2 The precision of this test will vary depending on the material being leached. 
APPENDIX C 

MERCURY INFORMATION CLEARINGHOUSE 

REPORTS 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION 

BY-PRODUCTS 

ACKNOWLEDGMENT AND DISCLAIMERS

 This report was prepared under contract with the Canadian Electricity Association (CEA) 

and supported by funding from that organization, the Canadian Council of Ministers of the 

Environment, the U.S. Department of Energy (DOE) National Energy Technology Laboratory 

(NETL) Cooperative Agreement No. DE-FC26-98FT40321, and the Center for Air Toxic 

Metals® (CATM®) Program at the Energy & Environmental Research Center (EERC). However, 

any opinions, findings, conclusions, or recommendations expressed herein are the author(s) and 

do not necessarily reflect the views of any of the above-mentioned organizations. The authors 

also acknowledge preliminary funding from the Utility Solid Waste Activities Group for a 

similar effort to assemble data on mercury releases from coal combustion by-products. 

EERC DISCLAIMER

 LEGAL NOTICE This research report was prepared by the EERC, an agency of the 

University of North Dakota, as an account of work for the CEA and supported by funding from 

that organization, DOE NETL, and the CATM® Program at the EERC. Because of the research 

nature of the work performed, neither the EERC nor any of its employees makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the accuracy, 

completeness, or usefulness of any information, apparatus, product, or process disclosed, or 

represents that its use would not infringe privately owned rights. Reference herein to any specific 

commercial product, process, or service by trade name, trademark, manufacturer, or otherwise 

does not necessarily constitute or imply its endorsement or recommendation by the EERC. 

U.S. GOVERNMENT DISCLAIMER

 This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 
REPORT AVAILABILITY 

 This report is available to the public from the National Technical Information Service, U.S. 

Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders 

accepted at (703) 487-4650 and the CEA Mercury Program Web site 

(www.ceamercuryprogram.ca).
i 

TABLE OF CONTENTS 

LIST OF FIGURES ........................................................................................................................ ii 

LIST OF TABLES.......................................................................................................................... ii 

EXECUTIVE SUMMARY ...........................................................................................................iii

INTRODUCTION .......................................................................................................................... 1 

MERCURY POLICY ..................................................................................................................... 2 

QUARTER 4 FOCUS: RERELEASE OF MERCURY FROM COAL COMBUSTION 

BY-PRODUCTS............................................................................................................................. 4 

BACKGROUND ............................................................................................................................ 5 

Mercury and CCBs................................................................................................................ 5 

Anticipated Impacts of Proposed Mercury Control Technologies on CCBs ........................ 7 

STABILITY OF MERCURY ON CCBs........................................................................................ 9 

Leaching .............................................................................................................................. 10 

Vapor Release ..................................................................................................................... 14 

Microbiological Vapor-Phase Release................................................................................ 16 

INTERPRETATION AND CONCLUSIONS.............................................................................. 16 

UPCOMING EVENTS................................................................................................................. 18 

CONTACT INFORMATION....................................................................................................... 19 

REFERENCES ............................................................................................................................. 20 
ii 

LIST OF FIGURES 

1 Categorization of trace elements based on volatility. ........................................................... 7 

2 Leachate vs. total Hg; nondetects are shown as negative values. ....................................... 13 

LIST OF TABLES 

1 Leaching Results ................................................................................................................. 11 

2 Total Hg Concentrations in Fly Ash and Hg Concentrations in SPLP Extracts ................. 12 

3 Coal Fly Ash and Leachate (60-day) Mercury Contents .................................................... 12 

4 Mercury and Sulfur in Ash.................................................................................................. 14

5 Fly Ash Volatilization Results – Hg Concentration............................................................ 15
iii 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION 

BY-PRODUCTS 

EXECUTIVE SUMMARY 

The topic for this fourth quarterly report is Rerelease of Mercury from Coal Combustion 

By-Products (CCBs). The stability of mercury associated with CCBs is an issue that has only 

recently been under investigation, but it has become a more significant issue as the utility 

industry begins to develop, test and, eventually, install mercury emission controls that may 

increase the mercury associated with CCBs. The reasons for evaluating the rerelease of mercury 

from CCBs are 1) to determine the stability of mercury captured on CCBs and 2) to aid utilities 

in determining and understanding changes in CCBs associated with mercury control and 

associated CCB management. 

 Mercury can be present in quantifiable levels in CCBs, and the mechanisms that allow 

mercury to be removed with CCBs have become the focus for many developing mercury control 

technologies. Mercury is most likely to be found in fly ash and flue gas desulfurization (FGD) 

materials and not in bottom ash and boiler slag because of the relatively high temperatures at 

which bottom ash and boiler slag are formed and removed from coal combustion systems. As a 

result of improved mercury removal, especially through particulate control devices and FGD 

systems, increased mercury concentrations are likely to be observed in respective CCBs. 

 Potential rerelease mechanisms for mercury from CCBs are identified as 1) direct 

leachability, 2) vapor-phase release at ambient and elevated temperatures, and 3) biologically 

induced leachability and vapor-phase release. 

 Currently, the incorporation of sorbents into the fly ash stream, resulting from injection of 

sorbent into the flue gas, poses the highest potential impact on CCBs. At this time, the most 

likely sorbent candidate is activated carbon. The second most likely impact to CCBs from 

mercury control technologies is in the area of FGD materials, especially in materials generated 

from wet FGD systems.

 Existing data indicate that the mercury content of fly ash and FGD materials collected 

during tests of mercury control technologies can be significantly increased over the mercury 

content currently being generated without mercury emission controls in place. Since many 

mercury control systems currently under development are using carbon sorbents to remove 

mercury from the flue gas, it is important to note that the unburned carbon associated with some 

currently generated fly ash has similar sorbent properties as activated carbon used for mercury 

removal. Both samples of fly ash with unburned carbon and fly ash with activated carbon sorbent 

have shown good performance in evaluations of mercury stability. 

 The data assembled and summarized here indicate that mercury associated with CCBs is 

stable and highly unlikely to be released under most management conditions, including 

utilization and disposal. Therefore, existing CCB management options are expected to be 
iv 

environmentally sound options for CCBs from systems with mercury control technologies 

installed. 
1 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION 

BY-PRODUCTS 

INTRODUCTION 

 The Canadian Electricity Association (CEA) identified a need and contracted the 

Energy & Environmental Research Center (EERC) to create and maintain an information 

clearinghouse on global research and development activities related to mercury emissions from 

coal-fired electric utilities. With the support of the CEA, the Center for Air Toxic Metals®

(CATM®) Affiliates, the U.S. Department of Energy (DOE), and the Canadian Council of 

Ministers of the Environment (CCME), the EERC is developing comprehensive quarterly 

information updates to provide a detailed assessment of developments in mercury monitoring, 

control, policy, and related research advances. 

 Ongoing developments in the area of mercury regulations for coal-fired power plants in 

Canada in the form of Canadawide Standards (CWS) and the United States in the U.S. 

Environmental Protection Agency’s (EPA’s) Proposed Utility Mercury Reduction Rule illustrate 

the need for effective mercury control strategies for coal-fired electric utilities. In previous 

quarterly reports, various mercury control technologies were reviewed in detail. Additionally, a 

review of the state of technology for mercury measurement was provided in the second quarterly 

report. As more emphasis is placed on mercury removal from flue gas, increased mercury 

concentrations may be found in the various coal combustion by-products (CCBs) which are 

valuable raw materials in the concrete and wallboard industries among others. The fate of these 

by-products and the mercury contained within them is of significant interest if mercury from coal 

combustion is going to be eliminated from the global pool. It is of vital importance that mercury 

removed from coal combustion flue gas and present in CCBs is stable and not hazardous to the 

environment or human health. If mercury concentrations of these CCBs is significantly increased 

over that of currently produced CCBs, utilities, CCB users, regulators, and others may need to 

modify management options to ensure the environmentally sound management of these 

materials. Therefore, significant research has been conducted to evaluate the mechanisms by 

which mercury is associated with fly ash and scrubber effluents. A review of the fate of mercury 

in coal combustion by-products is provided in this quarterly report. 

 In order to adequately address the many topics pertinent to mercury research and 

development and provide the detail necessary for the various stakeholders to make informed 

decisions, selected topics will be discussed in detail in each quarterly report. Issues related to 

mercury from coal-fired utilities include the general areas of measurement, control, policy, and 

transformations. Specific topics that have been addressed in previous quarterly reports include 

the following: 

• Quarterly 1 – Sorbent Control Technologies for Mercury Control 

• Quarterly 2 – Mercury Measurement 
2 

• Quarterly 3 – Advanced and Developmental Mercury Control Technologies 

As advancements are made in these previously covered topics, updates will be provided as a 

secondary topic of the quarterly report. However, to date no significant advancements in 

technology development or measurement control have been identified. 

Topics that will be addressed in upcoming quarterly reports include, but are not limited to, the 

following: 

• Mercury policy – updated each quarter based on available information 

 – Upcoming events and news releases 

 – Regulation, policy, compliance strategies, and health developments 

• Baseline mercury levels and emissions 

• Mercury control 

 – Summary of large-scale test activities and associated economics 

 – Mercury oxidation and control for scrubbed systems 

 – Multipollutant control strategies 

 – Summary of mercury-related economics for commercial systems 

• Mercury chemistry and transformations 

 – Mercury chemistry fundamentals, modeling, prediction, and speciation 

 – Mercury fate and transport – impacts on health 

MERCURY POLICY 

 The CCME has been in the process of developing CWS for mercury since 1998 for several 

significant mercury-emitting sectors and products. Standards have been completed for base metal 

smelters, incinerators, mercury-containing lamps, and dental amalgam wastes. A CWS for 

mercury emissions from coal-fired electric power-generating plants is currently under 

development. Canadian coal-fired generating companies have embarked on a multiyear program 

to improve the information base around mercury measurement and control that will aid in the 

development of the CWS. A key component of the CEA Mercury Program is the Coal, Residue, 

and Flue Gas Sampling and Analysis Program that companies have undertaken. This program 

has generated a rich database around mercury emission inventories and management to inform 

this decision-making process. To date, data have been collected from 16 different power plants 

operated by ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia 

Power, Ontario Power Generation, SaskPower, and TransAlta. The preliminary data can be 

accessed on the program Web site: http://www.ceamercuryprogram.ca. The data is currently 

undergoing verification and analysis by the CCME and the coal-fired generating companies to 

ensure the data set is robust for consideration in the 2005 CWS development process. 

 Another componenet of the CEA Mercury Program is the Laboratory Round Robin, a 

review of analytical laboratories. Developed by CEA member companies and funded by CCME, 
3 

this program consisted of a two-phased analysis and quality assurance program. Mercury 

concentrations in fuel, by-products, and stack gas samples tend to exist at very low levels; 

therefore, accurate laboratory analysis is critical to ensuring an effective mercury inventory 

program. Phase I of this program has been completed and focused on assessing participating 

laboratories by analyzing standard samples over a 6-month period. Phase II of the Laboratory 

Round Robin provided ongoing quality assurance for the data collection program and 

benchmarked several common Canadian coals for mercury and other coal-specific properties. 

Laboratories participating in the program tended to do very well. For more information regarding 

the Laboratory Round Robin, go to http://www.ceamercuryprogram.ca. 

 In the United States, EPA has received 586,000 comments on the Proposed Utility 

Mercury Reduction Rule after it extended the comment period to June 29, 2004. From this record 

number of comments, including 4800 unique comments, approximately 200 comments contained 

substantial content and ranged in length from five to ten pages. 

 In his address to the 2004 annual Air and Waste Management Mega Symposium, EPA 

Administrator Mike Leavitt stated that EPA is in the process of reviewing the comments which 

will be summarized in a comment response document in advance of the March 15 deadline for 

the final rule. Additionally, he laid out five guiding principles that EPA is using in devising the 

final mercury rule. The rule will: 

1) Concentrate on the protection of children and pregnant women. 

2) Stimulate and encourage early implementation of new technology. 

3) Leverage the $50 billion investment of the Clean Air Interstate Rule to reduce total 

 mercury emissions. 

4) Take into account the need to maintain America’s competitiveness worldwide. 

5) Be one component of many efforts to reduce mercury emissions. 

 Once the EPA comment response document becomes available, a summary will be 

provided in the following quarterly report. 

 In Europe, the European Commission recently issued a consultation document on mercury 

which evaluated mercury emissions, production, trade, and use and reviewed the health and 

environmental impacts of mercury. The original focus of the effort was Europe’s chlor-alkali 

industry, which is the largest user of mercury in Europe; however, it is in the process of phasing 

out its use. A copy of the Commission’s document is available at the following Web site: 

http://europa.eu.int/comm/environment/chemicals/mercury/pdf/consultation.pdf. 
4 

 Currently, coal combustion in power plants is the largest single source of mercury 

emissions in Europe. However, the issue of mercury emissions is complicated by two opposing 

trends. In response to concerns over mercury, emission standards are tightening. However, 

unlike many other parts of the world, mercury emissions and environmental concentrations in 

Europe appear to be falling according to data collected between 1990 and 2000 and summarized 

at the aforementioned Web site. Based on this data, it is unclear what strategy the Commission 

will take regarding mercury emissions, and unlike the United States, it is not certain that Europe 

will introduce mercury controls at an early stage. 
5 

QUARTER 4 FOCUS: RERELEASE OF MERCURY FROM COAL COMBUSTION 

BY-PRODUCTS 

 Mercury and other air toxic elements can be present in fly ash, flue gas desulfurization 

(FGD) material and, to a lesser extent, bottom ash and boiler slag. The mercury that can 

associate with CCBs is a function of the mercury content of the coal used, the coal properties, 

the combustion technology, and the emission control technologies at the plant. Generally 

speaking, mercury released from the combustion of coal remains in the gaseous state until 

cooling to temperatures typical of back-end emission control equipment, at which point it either 

reacts with components of the flue gas and is removed from the system as particulate-bound 

mercury in the ash, a sulfur compound with FGD control, or is emitted out the stack. 

 Mercury emission control technologies are being developed to remove mercury from the 

flue gases and, in many cases, these technologies are designed to incorporate the mercury 

removed from the flue gas into the fly ash or FGD material. The stability of mercury associated 

with CCBs is an issue that has only recently come under investigation, but it has become a 

prominent question as the industry strives to develop and test mercury emission controls that 

may consequently increase the mercury associated with CCBs. The primary reason for 

evaluating the rerelease of mercury from CCBs is to aid utilities in determining and 

understanding changes in CCBs associated with mercury control and how these changes may 

impact CCB management. 

 The rerelease mechanisms for mercury from CCBs are 1) direct leachability and 2) vaporphase release at ambient and elevated temperatures. Both leachability and vapor-phase transport 

can be impacted by microbiological action on the CCBs. 

BACKGROUND 

Mercury and CCBs 

 Mercury can be present in quantifiable levels in CCBs. It is most likely to be found in fly 

ash and FGD materials and not in bottom ash and boiler slag because of the relatively high 

temperatures at which bottom ash and boiler slag are formed and removed from coal combustion 

systems. 

 Historically, data on mercury concentrations in fly ashes have varied widely, but 

leachability of mercury has generally fallen below detection limits (1–4). Hassett et al. (5–7) 

reported mercury concentrations ranging from <0.01 to 2.41 ppm in samples of fly ash from all 

ranks of coal from both the eastern and western United States. Consistent with what is known 

about the chemistry of mercury in combustion systems, the average mercury content of fly ash is 

higher than that for bottom ash or slag and increases with the carbon content of the ash (8, 9). 

The mercury contents of FGD scrubber materials are, in turn, higher on average than those of fly 

ash (10). Concentrations of 39 and 70 ppm were reported by DeVito and Rosenhoover (11) and 

DeVito (12) for two FGD materials. 
6 

 Nearly 100% of the mercury present in coal exits the boiler with the flue gas. The 

speciation of that mercury however is highly influenced by the composition of the flue gas (12). 

Data from the EPA Information Collection Request (ICR) allowed for some generalizations to be 

made regarding the potential for various CCBs to capture mercury. Hot-side electrostatic 

precipitators (ESPs) do not allow capture of mercury on the fly ash because the temperature is 

too high, but cold-side ESPs and fabric filters operate at temperatures that do allow some 

mercury to be removed from the flue gas. Fabric filters tend to remove significant percentages of 

both elemental and oxidized mercury because of the excellent gas–solids contact as the flue gas 

moves through the dust cake on the filter. Wet FGD (WFGD) systems and spray dryer absorbers 

have been shown to be effective in removing oxidized mercury from flue gas. Additional 

information on the results collected in the EPA ICR can be found in other sources (13–16). CEA 

has a program in place with eight coal-fired power generation companies in Canada designed to 

develop information associated with mercury emissions from coal-fired generation and to find 

cost-effective and efficient management options for mercury emissions (more information is 

available at the following Web site: http://www.ceamercuryprogram.ca/EN/ 

program_overview.html). The CEA program collected information on the mercury content of 

CCBs, and the data assembled are under review. 

 The EPA ICR data did not include information on the concentrations of mercury on the 

CCBs generated at the test facilities, so it is an inference that the noted mercury reductions 

indicate an associated mercury capture on the CCBs. It is logical to conclude that at least some 

mercury can be captured by fly ash and/or FGD material. It is known that the mercury can be 

present in the flue gas as either elemental and/or oxidized species and that both elemental and 

oxidized mercury can be sorbed on carbon. Mercury can be physically or chemically sorbed on 

carbon, so it can be assumed that unburned carbon present in fly ash can sorb mercury by either 

or both of these mechanisms. While elemental mercury can be sorbed on carbon, it is actually 

transformed to oxidized mercury (17), implying that its stability on the carbon will be similar to 

that of oxidized mercury. The mechanism of mercury capture on unburned carbon is expected to 

be equivalent to that of activated carbon introduced into the flue gas as a means of mercury 

removal and control. However, insufficient data exist to extrapolate that assumption to include 

modified activated carbons such as halogenated or sulfuric-impregnated carbon or other 

modified carbon sorbents under development. In many cases, the quantities of carbon sorbent 

needed for mercury control are not expected to be higher than the level of unburned carbon 

already found in some fly ashes. The activation of the carbon sorbent, however, is anticipated to 

be problematic for use of these fly ashes as a mineral admixture in concrete because the activated 

carbon has been shown to sorb standard air-entraining admixtures and limit the function of the 

admixture to produce an air-entrained concrete, which is needed for numerous applications. 

 The EPA ICR data strongly imply that certain coal fly ashes may exercise a catalytic effect 

on the oxidation of elemental mercury. Inorganic compounds such as manganese oxide, ironcontaining compounds, and chromium and nickel oxides have been shown to catalyze mercury 

oxidation (18, 19), but various tests with the addition of some of these compounds to simulated 

flue gas did not produce the anticipated oxidation of mercury (20, 21). The mechanism of 

sorption of mercury on fly ash is extremely complicated and has not yet been fully investigated. 
7 

Anticipated Impacts of Proposed Mercury Control Technologies on CCBs 

 Proposed mercury emission controls have the potential to impact fly ash and FGD 

materials because mercury is highly volatile and should leave the combustion zone in the flue 

gas. As noted in Figure 1, mercury should be volatilized and emitted fully in the vapor phase in 

combustion systems. Mercury in the vapor phase in the flue gas has the potential to be sorbed 

onto the fly ash, carbon (either unburned carbon or sorbent), other sorbents, and the FGD 

reagent, or it may be emitted. The highest potential for mercury controls to impact CCBs is 

through the use of sorbent injection technologies that will incorporate the sorbent into the fly ash 

stream. The most likely sorbent candidate is activated carbon, even though other sorbents have 

been and are being tested. Testing at four full-scale boilers that measured mercury across 

particulate control devices gives some insight to the importance of particulate control in mercury 

removal and indicates that increased carbon relates to increased mercury removal. Even though 

no sorbent injection or other add-on mercury control technology was in place during these tests, 

the unburned carbon present in the fly ash provided significant mercury removals. Mercury 

removals ranged from a low of 28% for an ESP to between 61% and 99% for units equipped 

with reverse-gas baghouses (22). The highest mercury removals were observed where there was 

a high level of unburned carbon in the fly ash (high loss on ignition [LOI]). Pilot tests reinjecting 

power plant fly ashes ahead of a reverse-gas baghouse indicated removals between 13% and 

80% at temperatures in the range of l35°–l60°C (275°–320°F), and again, removals increased 

with increased LOI. It must be noted that LOI is not equivalent to carbon content of ash. 

Energy &

Environmental

Research 

Center

Categorization of Trace Metals 

Based on Volatility

Class III

Volatilized and emitted fully 

in the vapor phase – Not 

enriched in the fly ash

Class II

Enriched in the fly ash and 

depleted in the bottom ash

Class I

Equally distributed between 

bottom ash and fly ash

Hg

Br Cl F

B Se I

Increasing Volatility

Eu Hf La Mn Rb

Sc Sm Th Zr

As Cd Ga Ge Pb

Sb Sn Te Ti Zn

Ba Be Bi Co

Cr Cs Cu Mo Ni Sr

Ta TI U V W

Figure 1. Categorization of trace elements based on volatility. 
8 

 At tests performed at Wisconsin Electric’s Pleasant Prairie Power Plant, Unit 2, in 2001 

(23), activated carbon injection (ACI) resulted in mercury removals of 40%–70%, with increased 

removals correlating to increased carbon injection. The LOI of the fly ash produced without 

sorbent injection at Pleasant Prairie was approximately 0.5% but was increased to as high as 

3.5%. More noteworthy than the LOI increase was the impact of that increase on the 

performance of the fly ash–sorbent mixture in the Foam Index Test, which provides an indication 

of the appropriateness of the fly ash to be used with an air-entraining agent (AEA). The fly ash–

sorbent mixture not only failed the Foam Index Test, but the fly ash from Unit 2 continued to fail 

the test for 5 weeks after the conclusion of the sorbent injection tests. The presence of carbon in 

fly ash has been reported to impact the use of fly ash in concrete. The impact relates to air 

entrainment in concrete. AEAs are used to facilitate the incorporation of very small air bubbles 

into the concrete mix. The presence of these air voids provides improved freeze-thaw durability 

of the concrete. For commonly used AEAs, the presence of carbon interferes with the formation 

of the air voids by sorbing the AEA. Early in the development of specifications for fly ash for 

use as a mineral admixture in concrete, an upper limit of 6.0% LOI was set for fly ash in order to 

address this technical issue associated with unburned carbon in fly ash. The potential addition of 

activated carbon is expected to exacerbate the problem associated with carbon in fly ash and its 

use in concrete. Preliminary results, such as those from the Pleasant Prairie tests, indicate that 

the long-standing limit of 6.0% LOI will not be adequate to determine the appropriateness of fly 

ash activated carbon mixtures for use in concrete. Work addressing this issue is under way by 

various academic and industrial groups and includes development of AEAs which will perform 

adequately even with higher carbon content fly ash, admixtures that deactivate the carbon and 

allow successful use of standard AEA, and carbon removal systems. High carbon fly ash is also 

used as a feedstock component for cement clinker production which is a high-temperature 

process. The chemistry of mercury suggests that mercury associated with fly ash (or the carbon 

in fly ash) will be released as vapor. Since there is evidence that noncarbon sorbents sorb 

mercury, research needs to be undertaken to determine the fate of mercury in a cement kiln and 

the associated emission control systems. 

 Senior et al. (23) also reported on activated carbon sorbent injection tests at Alabama 

Power’s Gaston Station, which has a hot-side ESP and a COHPAC (compact hybrid particulate 

collector), which provides a second particulate collection after the ESP for polishing purposes. 

This system allows the injection of sorbent after the bulk of the fly ash has been collected and 

separate collection of any remaining fly ash in the flue gas stream along with the mercury-loaded 

sorbent. 

 Noncarbon sorbents have been tested for their mercury removal potential, with the intent 

of identifying sorbents that would capture and hold mercury and have a reduced impact on the 

fly ash for potential utilization especially in concrete (24, 25). One fly ash from a western 

subbituminous coal was shown to have a significant mercury sorption capacity after heating to 

remove all carbon (22), and mercury capture was improved by spray cooling to reduce the gas 

temperature to 110°C (230°F). 

 Another potential impact to CCBs from mercury control technologies is in the area of 

calcium-based FGD materials. It has been shown in field tests (26–28) that WFGD is successful 
9 

at removing a high percentage of oxidized mercury from the flue gas stream. Elemental mercury 

is not removed by WFGD, but existing WFGD systems capture approximately 90% of the 

mercury (II) at essentially no cost to the utility. Studies to enhance the capture of mercury in 

WFGD systems, generally by enhancing the oxidized mercury in the flue gas, are under way 

(29–38). Studies are also being performed on removing elemental mercury in WFGD systems as 

well as on increasing the percentage of oxidized mercury that is removed. The use of WFGD 

systems for mercury control has the potential to facilitate multipollutant control and may provide 

some impetus for utilities to consider WFGD systems over other SO2 controls for DOE Phase II 

(39) and new fine-particulate control standards. It has been shown that FGD material generated 

from wet systems can be oxidized to produce gypsum and that mercury present in the WFGD 

material is partitioned into the gypsum, implying that the mercury is not readily leached from the 

gypsum (40). The primary effort in the area of mercury emission control using FGD systems has 

been performed using wet systems, although other types of calcium-based FGD systems also are 

expected to remove oxidized mercury from flue gas at varying efficiency levels. 

STABILITY OF MERCURY ON CCBs 

 As previously noted, data on mercury concentrations in fly ashes are varied. CEA data 

(http://www.ceamercuryprogram.ca/EN/program_overview.html) indicates mercury 

concentrations ranging from <0.002 to 1.221 ppm in fly ash and from 0.001 to 0.342 ppm in 

bottom ash. Hassett et al. (5–7) reported mercury concentrations ranging from <0.01 to 2.41 ppm 

in samples of fly ash from full-scale coal-fired power plants from all ranks of U.S. coal. 

Concentrations of 39 and 70 ppm were reported by DeVito and Rosenhoover (11) and DeVito 

(12) for two FGD materials. The mercury content of FGD material is higher on average than the 

mercury content of fly ash which is consistently higher than the concentrations found in bottom 

ash or boiler slag (10). The mercury concentration of fly ash tends to increase with the carbon 

content of the ash (8–9). Recently, the EERC reported that the mercury content of fly ash and 

FGD collected during tests of mercury control technologies can be significantly increased with 

samples containing a total mercury concentration as high as 120 ppm reported. However, of 

21 samples collected from mercury control demonstrations, only 6 had mercury concentrations 

greater than those noted for samples from systems without mercury control. Those six samples 

had mercury concentrations ranging from 4.7 to 120 ppm. 

 Limited data on fly ash–carbon sorbent mixtures (eight total samples) indicate a range of 

0.2–5.5 ppm total mercury content, with only two samples from one location providing data 

indicating mercury content greater than 1 ppm mercury. The limited data do not provide 

adequate evidence that mercury contents of fly ash–carbon sorbent mixtures will be consistently 

higher than fly ash produced without mercury emission controls installed. Senior and Bustard 

(23) reported mercury concentrations in the range of 10–100 ppm in spent sorbent from test runs 

using the COHPAC system. These data points should be considered separately from samples of 

fly ash or FGD material that may be impacted by mercury emission controls. 

 The total concentration of mercury on CCBs or sorbents cannot be used as an indicator of 

stability. The stability of mercury on CCBs or sorbents can only be evaluated by subjecting the 
10 

sample to a variety of laboratory tests that expose the material to conditions that simulate those 

in field settings for realistic management options for the material in question. 

Leaching1

 Various leaching methods are available to evaluate CCBs and other materials for 

environmental performance, but current data on the leachability of mercury from CCBs has been 

generated primarily by use of the TCLP (toxicity characteristic leaching procedure) and the 

SGLP–LTL (synthetic groundwater leaching procedure–long-term leaching). The TCLP, 

frequently applied to CCBs, involves the extraction of contaminants from a 100-g size-reduced 

sample of waste material with an appropriate extraction fluid. A 20:1 liquid-to-solid (L/S) ratio 

(mass/mass, m/m) is employed, and the mixture is rotated for 18 ± 2 hr at 30 rpm using a rotary 

agitation apparatus. The extraction fluid used for the extraction depends on the alkalinity of the 

waste material. Very alkaline waste materials are leached with a fixed amount of acetic acid 

without buffering the system (pH 2.88 ± 0.05), while other waste materials are leached with 

acetic acid buffered at pH 4.93 ± 0.05 with 1-N sodium hydroxide. After rotation, the final pH is 

measured, and the mixture is filtered using a glass fiber filter. The filtrate is collected in an 

appropriate container, and preservative may be added if needed. The filtrate is analyzed for a 

number of constituents. EPA now recognizes that the TCLP is an inappropriate test for use with 

CCBs. The SGLP–LTL is a procedure developed at the EERC. The SGLP–LTL was designed to 

use a synthetic groundwater for the leachate to more closely simulate environmental conditions 

and to include longer-term leaching time frames for reactive CCBs. In many cases, the SGLP–

LTL uses distilled, deionized water because specific site information for the management options 

to be applied to the CCB is unavailable. The complete SGLP–LTL usually includes leaching 

times of 18 hours, 30 days, and 60 days. However, LTL is only necessary for alkaline samples 

(pH >10), because CCB samples with pH values below 10 do not undergo long-term hydration 

reactions that impact leachate characteristics. 

 The amount of mercury leached from currently produced CCBs is extremely low and 

generally does not represent an environmental or rerelease hazard. Concentrations of mercury in 

leachates from fly ashes and FGD material using either the TCLP or the SGLP are generally 

below detection limits (0.005 to 0.05 μg/L) (5, 11, 12, 24, 30, 31, 33). 

 Mercury leachate concentrations from various types of leaching tests (both batch and 

column) for CCBs resulting from the use of mercury control technologies have been reported. In 

addition to TCLP and SGLP, the synthetic precipitation leaching procedure (SPLP) and synthetic 

acid leaching (SAL) batch tests have been used as short-term methods. LTL, a component of the 

SGLP, has also been performed using 30- and 60-day equilibration periods. 

 

1

 The authors of the various references have reported data in several different formats. The following concentrations 

are equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per 

trillion) = pg/g, ng/L. The EERC has used ppm, ppb, and ppt to express concentrations associated with solid 

materials and vapor-phase releases. μg/L and ng/L have been used for concentrations in liquids such as leachate 

concentrations. 
11 

 Senior et al. (23, 41) reported that little or no detectable Hg was leached by TCLP or 

SGLP from fly ash samples resulting from powdered activated carbon (PAC) injection 

demonstrations at four coal-fired power plants. As shown in Table 1, baseline fly ash, fly ash + 

sorbent, and COHPAC samples all gave similar leaching results, illustrating very low 

concentrations. 

Table 1. Leaching Results (leached by the EERC) (23, 41) 

 Hg in, μg/L 

Plant Location 

Injection Rate, 

lb/MMacf TCLP SGLP 

Salem Harbor ESP Row A (control) 0 0.034 <0.01 

Salem Harbor ESP Row A 10 <0.01 <0.01 

Salem Harbor ESP Row A 10 <0.01 <0.01 

Brayton Point New ESP 0 <0.01 0.01 

Brayton Point Old ESP1

 0 0.02 0.05 

Brayton Point New ESP 10 0.07 0.03 

Brayton Point Old ESP1 10 0.03 0.01 

Brayton Point New ESP1

 20 <0.01 0.01 

Brayton Point Old ESP 20 0.02 0.02 

Gaston COHPAC B-side 1.5 0.01 <0.01 

Gaston COHPAC B-side 1.5 NA2 <0.01 

Gaston COHPAC B-side 1.5 <0.01 <0.01 

Pleasant Prairie ESP hopper composite 10 <0.01 <0.01 

Pleasant Prairie ESP hopper composite 10 <0.01 <0.01 

Pleasant Prairie ESP hopper composite 10 <0.01 NA 

1

 Sorbent injected downstream of the old ESP. 

2

 Not applicable. 

 Gustin et al. (42, 43) and Ladwig (44) also reported on the leachability of Hg from the 

Pleasant Prairie and Brayton Point PAC injection tests using SPLP (see Table 2). An increase in 

the Hg leachate concentration was noted between the baseline and PAC injection samples by 

Gustin et al. for the Pleasant Prairie samples, which were all collected from the same ESP. The 

Brayton Point baseline and test samples were collected at different points, so a direct comparison 

cannot be made. 

 Fly ash samples from pilot-scale test burns using ACI and the Advanced HybridTM filter 

were leached using SGLP and LTL (45). The SGLP and 30-day LTL leachate results were below 

the limit of quantification (i.e., <0.01 ppb); however, the 60-day LTL leachates indicated a small 

release of mercury (Table 3). Pavlish et al. (45) reported that the results indicate that the fabric 

filter and Advanced HybridTM filter were more effective in capturing particulate Hg relative to 

the ESP. 
12 

Table 2. Total Hg Concentrations in Fly Ash and Hg Concentrations 

in SPLP Extracts (adopted from Gustin et al. [43]) 

Sample Total Hg, ppb Leached Hg, ng/L 

S2A-1 (base) 247 0.65 

S2A-1a 0.8 

S2A-1a

 0.6 

S2A-1a 0.2 

S2A-2 (ACI) 2300 NDb

S2A-2a

 ND 

S2A-2a 2.9 

S2A-3 (ACI) 1040 3 

S2A-3a 6.9 

S2A-3a 10.7 

B7A-1 (base) 670 2.6 

B7A-1a

 2.6 

B7A-2 (ACI) 752 ND 

B7A-2a ND 

B7A-3 (ACI) 670 ND 

 a Replicated measurements. b Not detected. 

Table 3. Coal Fly Ash and Leachate (60-day) Mercury Contents (adapted from Pavlish et 

al. [45]) 

Fly Ash (leachate) Mercury, ppm (ppb) 

Coal Activated Carbon 

Injection 

Rate, g/hr ESP FF 

Advanced 

HybridTM Filter 

Poplar River NAa NA 0.030 (<0.01) NA NA 

Poplar River Luscar char 40–150 0.218 (0.032) NA NA 

Poplar River Luscar char 10–50 0.011 (<0.01) 8.66 (<0.01) NA 

Poplar River Luscar char 20–120 NA NA 1.15 (<0.01) 

Freedom Fine Luscar char 15–115 0.198 (<0.01) NA NA 

Freedom DARCO FGD 10–40 Not analyzed 17.8 (0.057) NA 

Freedom Luscar char 10–40 0.040 (<0.01) 5.73 (<0.01) NA 

Freedom Luscar char 10–40 NA NA 0.865 (<0.01) 

a

 Not applicable. 

 In early work at the EERC, 22 samples from full-scale power plants operating without any 

mercury controls were subjected to SGLP, and all resulting leachate mercury concentrations 

were <0.01 μg/L, with one exception where the leachate concentration was 0.018 μg/L (46). 

More recently, the EERC reported that SGLP leachate concentrations of mercury ranged from 

<0.01 to 0.05 μg/L and TCLP leachate concentrations of mercury ranged from <0.01 to 

0.14 μg/L (47). These data, which included evaluations of fly ash from systems with and without 

mercury controls in place, are shown in Figure 2. EERC researchers concluded from the data 

presented that there was no correlation between total mercury content and leachable mercury. 
13 

 Results of column leaching performed by Kazonich et al. (48) indicated that mercury 

leached at extremely low levels when subjected to leaching by solutions ranging from acidic to 

alkaline. Results of continuing work at DOE’s National Energy Technology Laboratory (NETL) 

using the column leaching procedure and multiple leaching solutions indicated that release of 

mercury from CCBs by leaching was not related to the total concentration of mercury in the 

sample (49). The NETL data also indicated that higher leachate concentrations were observed 

with the acetic acid leachate; however, NETL concluded that it was unlikely that leachate 

concentrations of mercury would exceed drinking water standards. 

 The use of sodium tetrasulfide (Na2S4) injection as a mercury control technology is being 

explored in pilot-scale facilities at Southern Research Institute (50). A bituminous and a 

subbituminous coal were tested and associated ash samples subsequently leached using TCLP. 

Leachate concentrations of mercury are shown in Table 4. An increase in total Hg content in the ash 

was noted for both coals with Na2S4 injection; however, on comparison to leachates from baseline 

ash, an increased mercury leachate concentration was only noted for the bituminous ash while the 

subbituminous ash had a lower mercury leachate concentration. 

 The effect of flue gas desulfurization used for Hg control has been reported by Richardson 

(51) and Golden (52). Associated TCLP leaching results for forced oxidation limestone 

processes were all <0.06 μg/L, while the single FGD material from a system using inhibited 

oxidation gave a mercury leachate concentration of 0.34 μg/L. Withum et al. (53, 54) leached a 

variety of Hg control technology CCBs with both TCLP and American Society for Testing and 

Materials (ASTM) D3987 tests. All samples had Hg leachate concentrations of <1.0 μg/L. 

Figure 2. Leachate vs. total Hg; nondetects are shown as negative values. 
14 

Table 4. Mercury and Sulfur in Ash (50) 

Run 

No. 

Coal 

Type Injection Condition 

Na2S4 in Flue 

Gas, ppmv 

Total Hg in 

Ash, ppb 

TCLP Hg, 

μg/L 

6 Bit.a Baseline condition 0 1.28 20.6 

7 Bit. 13.5 1.94 76.8 

8 Bit. Raised flue gas temperature 13.5 1.94 76.8 

9 Bit. Lowered flue gas temperature 13.5 1.94 76.8 

10 Bit. Normal temperature 6.8 NAb

 NA 

11 Bit. Repeat condition 2 13.5 NA NA 

12 Bit. Inject chlorine through burner 13.5 NA NA 

13 Bit. Half chlorine injection 13.5 2.20 69.9 

14 Bit. Maintain chlorine injection, turn 

off Na2S4 injection 

0 1.84 ± 0.28 70.4 

15 PRB Baseline 0 1.76 65.7 

16 PRB 12.2 1.93 0.342 

17 PRB 6.1 1.93 0.342 

18 PRB Return to baseline 0 1.93 0.342 

19 PRB Residual effect 2.9 1.93 0.342 

20 PRB Start fresh 2.9 NA NA 

21 PRB 6.1 NA NA 

22 PRB Increased air injection temperature 6.1 1.29 30.5 

a Bituminous coal. 

b Not applicable. 

 Leaching tests on four carbon sorbents were performed using TCLP. Detectable levels of 

mercury in the leachate were observed for only one sorbent (55). These preliminary results 

suggest that mercury is not readily leached from sorbents, which implies that the rerelease of 

mercury from spent sorbents such as those reported by Senior and Bustard (23) may not pose a 

significant management issue relative to leaching. 

Vapor Release2

 The release of mercury vapor from CCBs resulting from the use of Hg control technologies 

has been evaluated on a limited basis. Methods of determining the release include measuring the 

Hg in the air, capturing the Hg released over extended time periods, and evaluating the Hg 

content of the CCBs at varying time periods, which generally require very sensitive analytical 

techniques. Hassett and Heebink performed long-term ambient-temperature desorption 

experiments, and results indicated that five of the six CCBs analyzed acted as mercury sinks 

(56). 

 Butz and Smith (57) compared the total Hg content of CCBs initially and after 8 months in 

open and closed containers to determine offgassing. The results reported suggest that the Hg 

bound to the ash and/or activated carbon is fairly stable. 

 

2

 The authors of the various references have reported data in several formats. The following concentrations are 

equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per 

trillion) = pg/g, ng/L. 
15 

 Fly ash volatilization studies performed by Schwalb et al. (54) compared total mercury 

contents of several ash samples as-received and after exposure to elevated temperatures (100° 

and 140°F [37.7° and 60°C]) for 6 months with total mercury concentration measured at 3 and 6 

months. Results are shown in Table 5. 

 Table 5. Fly Ash Volatilization Results – Hg Concentration, ppm (54) 

3 month 6 month 

Plant ID As-Received 100°F 140°F 100°F 140°F 

3 0.09 ± 0.02 0.09 0.10 0.12 0.17 

6 0.29 ± 0.05 0.34 0.32 0.38 0.34 

6 0.19 ± 0.04 0.22 0.25 0.28 0.24 

6 0.69 ± 0.11 0.72 0.69 0.69 0.69 

4 0.08 ± 0.02 0.11 0.12 0.13 0.12 

4 0.08 ± 0.02 0.09 0.10 0.11 0.13 

 Gustin et al. (42, 43) and Ladwig (44) evaluated the Hg flux for CCBs. Results indicated 

that both baseline fly ash samples and those with activated carbon exhibited a net deposition of 

Hg on the fly ash. Deposition was greatest on the samples with activated carbon, leading Gustin 

et al. (42) to conclude that it was possible that the higher carbon in the ash facilitated 

atmospheric Hg uptake. 

 Gustin et al. (43) also evaluated Hg flux from fresh samples and samples exposed to air for 

9 months in order to determine the potential for reemission of deposited atmospheric Hg from 

ash. Experiments included the addition of water to the samples exposed to air which resulted in a 

difference in the Hg flux noted. Mercury deposited on dry ash, as previously noted, but results 

indicated that mercury was emitted from the wet ash. Gustin et al. (43) reported that the emission 

rate for the wet ash declined over time and returned to deposition. The addition of water to the 

fresh samples resulted in less of a difference in flux, indicating that Hg released after the 

addition of water was deposited atmospheric Hg and that the fresh ash did not have loosely 

bound, readily released Hg. 

 Limited information has been reported on the stability of mercury captured on sorbents 

(55). Results of thermal desorption tests indicate that mercury is thermally released from 

sorbents at temperatures considerably below the peak temperatures observed for fly ashes. 

Significant percentages of the mercury captured on the saturated sorbents were released upon 

heating above 135°C (275°F) in nitrogen, carbon dioxide, or flue gas; and 30%–50% of the 

original mercury capture capacity of the sorbent was regenerated after one or two regeneration 

cycles. Ambient release of mercury into a low flow rate of air was determined by collecting 

desorbed mercury on a sorbent. After correcting for blank determinations, essentially no mercury 

was released at ambient temperature (24°C [75°F]) from either of the sorbents tested. These data 

may be valuable in assessing the potential for rerelease of mercury from spent sorbents. 
16 

Microbiological Vapor-Phase Release 

 EERC researchers have reported on the microbiologically induced release of mercury 

vapor from CCBs (58) under aerobic and anaerobic conditions. Results of these preliminary 

experiments indicated that both elemental and organomercury were released. The experimental 

matrix consisted of eight flasks under aerobic conditions (using breathing-quality air) and eight 

flasks under anaerobic conditions (using argon). In each set of eight flasks, two contained only 

buffer, three contained a slurry of the CCB with buffer, and three contained a slurry of the CCB 

with buffer and glucose. An 80-g aliquot of CCB was placed in the flasks, and 100 mL of a 

phosphate buffer (with or without glucose) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bacterial culture added. Vapor traps collected the 

organo- and elemental mercury released from the system, and leachates were collected at the 

conclusion of the 30-day experiment. 

 At the 2004 Combined Power Plant Air Pollutant Control Mega Symposium, the EERC 

reported that oganomercury species were detected at very low levels both in the vapor and 

leachate generated from the microbiologically mediated release experiments (58). The EERC 

reported speciation of these organomercury compounds in leachates to be dimethyl and diethyl 

mercury but present at levels <5 ng/L (ppt). 

INTERPRETATION AND CONCLUSIONS 

 The data currently available on CCB mercury content and stability are limited because 

demonstration of mercury control technologies has only recently been initiated. Data on fly ash 

and FGD materials that have been generated at full-scale coal-fired power plants without 

mercury emission controls in place indicate that the concentration of mercury is relatively low 

for most samples, with total mercury concentrations ranging from <0.01 to 2.41 ppm. It has also 

been reported that the mercury content of fly ash and FGD collected during tests of mercury 

control technologies can be significantly increased with samples with a total mercury 

concentration as high as 120 ppm reported; however, of 21 samples collected from mercury 

control demonstrations, only six had mercury concentrations greater than those noted for 

samples from systems without mercury control. These data represent a very limited number of 

samples, types of mercury control, and combustion systems, but in 2004–2006, several tests of 

mercury emission control technologies at full-scale facilities will be performed, and a concerted 

effort is planned by DOE to fully evaluate the stability of mercury associated with the CCBs 

produced from these tests. 

 Carbon sorbents are expected to be used in many systems as part of the mercury control 

technologies, so it is important to note that normal activated carbon sorbents are not expected to 

perform differently than unburned carbon associated with fly ash, and samples of fly ash with 

unburned carbon have shown similar performance in evaluations of mercury stability. The 

stability of the mercury associated with these materials is similar to that of materials generated 

without mercury emission controls. Work on release of Hg from modified activated carbon 

sorbents is ongoing, and results are not available to assess the Hg behavior associated with these 

sorbents. 
17 

 Existing data indicate that the stability of mercury on fly ash and FGD material is similar 

for samples collected at sites without mercury controls and during tests of mercury control 

technologies. Data assembled and summarized in this document indicate that mercury associated 

with CCBs is environmentally stable under most management conditions, including utilization 

and disposal. The exception to this is exposure to high temperatures such as those that may be 

achieved in cement production. 

 Evaluations of CCBs that are collected from full-scale demonstration of mercury control 

are needed to confirm the data available in the literature. The data do not sufficiently represent 

all of the variables that may be associated with CCBs generated when mercury controls are in 

place. Existing data indicate that present CCB management options are expected to be 

environmentally sound for CCBs from systems with mercury control technologies installed, but 

information that should become available in the next few years is expected to allow conclusions 

to be drawn from a broader and more representative sample set. 
18 

UPCOMING EVENTS 

By-Product Beneficial Use Summit 

November 8, 2004, Kansas City, Missouri 

http://www.byproductsummit.com/papers.html 

Coal Combustion Products Partnership Workshop 

November 16, 2004, Atlanta, Georgia, contact William Aljoe (412) 386-6569 

http://fossil.energy.gov/news/events/ 

POWER-GEN International 

November 30–December 2, 2004, Orlando, Florida 

http://pgi04.events.pennnet.com 

229th ACS National Meeting 

March 13–17, 2005, San Diego, California 

http://oasys.acs.org/acs/229nm/topics.html 

World of Coal Ash 

April 11–15, 2005, Lexington, Kentucky 

http://www.acaa-usa.org/ASP/EventCalendar.ASP?YEAR=2005 

30th International Conference on Coal Utilization & Fuel Systems (formerly Clearwater Coal 

Conference) 

April 17–21, 2005, Clearwater, Florida 

http://www.coaltechnologies.com 

International Conference on Clean Coal Technologies for Our Future 

May 10–12 2005, Sardinia, Italy, contact Rodney Anderson (304) 285-4709 

http://fossil.energy.gov/news/events/ 

A&WMA 98th Annual Conference and Exhibition 

June 21–24, 2005, Minneapolis, Minnesota 

http://www.awma.org 

230th ACS National Meeting 

August 28–September 1, 2005, Washington, D.C. 

http://oasys.acs.org/acs/230nm/topics.html 

Air Quality V: Mercury, Trace Elements, and Particulate Matter Conference 

September 18–21, 2005, Washington, D.C. 

http://www.undeerc.org 
19 

CONTACT INFORMATION 

For more information, please contact: 

 Michael Holmes 

 Senior Research Advisor 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 mholmes@undeerc.org 

 (701) 777-5276 

 John Pavlish 

 Senior Research Advisor 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 jpavlish@undeerc.org 

 (701) 777-5268 
20 

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22 

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International Conference on Managing Hazardous Air Pollutants; Washington, DC, 

Nov 12–14, 1997. 

30. Amrhein, G.T.; Holmes, M.J.; Bailey, R.T.; Kudlac, G.A.; Downs, W.; Madden, D.A. 

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23 

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35. Hargrove O.W., Jr.; Carey, T.R.; Rhudy, R.G.; Brown, T.D. Enhanced Control of Mercury 

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Oxidation of Scrubber Sludge. Presented at the 5th International Conference on FGD and 

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24 

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Mercury Fly Ash Samples. In Proceedings of the Air Quality IV: Mercury, Trace 

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49. Kim, Ann. Aqueous Stability of Mercury on Fly Ash. Presented at the Mercury Control 

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Coal Ash Association 15th International Symposium on Management and Use of Coal 

Combustion Products, St. Petersburg, FL, Jan 27–30, 2003. 
25 

53. Withum, J.A.; Schwalb, A.M.; Statnick, R.M. Characterization of Coal Combustion ByProducts for the Re-Evolution of Mercury into Ecosystems. In Proceedings of the Air 

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Sept 9–12, 2002. 

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and By-Products. Presented at the Mercury Control Technology R&D Program Review 

Meeting, Pittsburgh, PA, Aug 12–13, 2003. 

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Surfaces. Presented at the Air and Waste Management Association 92nd Annual Meeting 

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International Ash Utilization Symposium; Lexington, KY, Oct 20–22, 2003. 

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58. Hassett, D.J.; Heebink, L.V.; Zacher, E.J. Determination of Organomercury Compounds 

from Microbiologically Medicated Mercury Release Experiments Using Gas 

Chromatography with SPME Sample Introduction after Boroethylation, Boropropylation, 

or Borophenylation. Presented at the Combined Power Plant Air Pollutant Control Mega 

Symposium, Washington, DC, Aug 30 – Sept 2, 2004. 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT 

ACKNOWLEDGMENT AND DISCLAIMERS

 This report was prepared under contract with the Canadian Electricity Association (CEA) and 

supported by funding from that organization, the Canadian Council of Ministers of the Environment, the 

U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Cooperative 

Agreement No. DE-FC26-98FT40321, and the Center for Air Toxic Metals® (CATM®) Program at the 

Energy & Environmental Research Center (EERC). However, any opinions, findings, conclusions, or 

recommendations expressed herein are the author(s) and do not necessarily reflect the views of any of the 

above-mentioned organizations. 

EERC DISCLAIMER

 LEGAL NOTICE This research report was prepared by the EERC, an agency of the University of 

North Dakota, as an account of work for CEA and supported by funding from that organization, DOE 

NETL, and the CATM Program at the EERC. Because of the research nature of the work performed, 

neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal 

liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, trademark, 

manufacturer, or otherwise does not necessarily constitute or imply its endorsement or recommendation 

by the EERC. 

U.S. GOVERNMENT DISCLAIMER

 This report was prepared as an account of work sponsored by an agency of the United States 

Government. Neither the United States Government, nor any agency thereof, nor any of their employees 

makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, 

completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that 

its use would not infringe privately owned rights. Reference herein to any specific commercial product, 

process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute 

or imply its endorsement, recommendation, or favoring by the United States Government or any agency 

thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the 

United States Government or any agency thereof. 

REPORT AVAILABILITY 

 This report is available to the public from the National Technical Information Service, U.S. 

Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders accepted at (703) 

487-4650 and the CEA Mercury Program Web site (www.ceamercuryprogram.ca).
i 

TABLE OF CONTENTS 

LIST OF FIGURES ....................................................................................................................... iv 

LIST OF TABLES.......................................................................................................................... v 

EXECUTIVE SUMMARY ........................................................................................................... vi 

INTRODUCTION .......................................................................................................................... 1 

CEA MERCURY PROGRAM OVERVIEW................................................................................. 3 

Laboratory Quality Assurance Assessment........................................................................... 4 

Mercury Research and Development .................................................................................... 4 

Mercury-Sampling and Analysis Program............................................................................ 5 

CEA Mercury Program Coal Data ........................................................................................ 5 

CEA Mercury Program Ash Data ......................................................................................... 7 

CEA Mercury Program Flue Gas Data ................................................................................. 8 

Mercury Policy...................................................................................................................... 9 

References ........................................................................................................................... 12 

SORBENT CONTROL TECHNOLOGIES FOR MERCURY CONTROL AND MERCURY 

CONTROL FIELD DEMONSTRATIONS (QUARTER 1 AND QUARTER 6 REPORTS) ..... 13 

Field Demonstrations of Carbon Injection.......................................................................... 13 

Field Demonstrations Using Chemically Treated Carbons................................................. 19 

Economics of ACI............................................................................................................... 20 

References ........................................................................................................................... 20 

MERCURY MEASUREMENT (QUARTER 2 REPORT).......................................................... 23 

Additional Experience with 40 CFR, Part 75, Appendix K Specifications ........................ 24 

QA/QC Requirements for Mercury Measurement RATAs................................................. 24 

Additional Experience Gained with Next-Generation Continuous Mercury Monitors ...... 25 

An Instrument-Based Reference Method for Mercury Measurement................................. 25 

ADVANCED AND DEVELOPMENTAL MERCURY CONTROL TECHNOLOGIES 

(QUARTER 3 REPORT).............................................................................................................. 27 

Pretreatment of the Coal to Remove Mercury .................................................................... 27 

Combustion Modification and in Situ Generation of Sorbents........................................... 28 

Non-Carbon-Based Sorbent, Amended Silicates ................................................................ 29 

Continued . . . 
ii 

TABLE OF CONTENTS (continued) 

Stationary Mercury Traps Positioned in the Flue Gas Stream............................................ 29 

 MerCAPTM................................................................................................................. 29 

 W.L. Gore & Associates, Inc.-Promoted Felt Filter Bag Inserts............................... 30 

 EnviroScrub Pahlman Process................................................................................... 30 

Combined Oxidation of NOx and Mercury................................................................ 31

LoTOxTM .................................................................................................................... 31 

ECO/Powerspan......................................................................................................... 31 

Mercury Control with the Advanced HybridTM Filter ......................................................... 32 

RERELEASE OF MERCURY FROM COAL COMBUSTION BY-PRODUCTS 

(QUARTER 4 REPORT).............................................................................................................. 33 

Stability of Mercury on CCBs............................................................................................. 33 

Leaching .............................................................................................................................. 35 

Vapor Release ..................................................................................................................... 35 

Elevated Temperature Vapor-Phase Rerelease.......................................................... 36 

Ambient Temperature Vapor-Phase Rerelease.......................................................... 36 

Microbiologically Mediated Release .................................................................................. 37 

Field Studies of Mercury Releases...................................................................................... 37 

Disposal Site Water Evaluations ............................................................................... 37

Field Vapor-Phase Releases ...................................................................................... 38 

Rerelease of Mercury from CCBs in Select Utilization Applications ................................ 39 

Summary ............................................................................................................................. 40 

References ........................................................................................................................... 41 

MERCURY FUNDAMENTALS (QUARTER 5 REPORT) ....................................................... 44 

Flue Gas Effects .................................................................................................................. 44 

Carbon Structure Effects ..................................................................................................... 44

Acid Promotion Effects....................................................................................................... 45

Mercury Oxidation Mechanism .......................................................................................... 47 

Halogenated Carbons .......................................................................................................... 47

Potential for More Effective Capture.................................................................................. 49 

References ........................................................................................................................... 50 

HEALTH ASPECTS OF MERCURY EMISSIONS (QUARTER 5 REPORT).......................... 52 

Environmental Hg ............................................................................................................... 56 

References ........................................................................................................................... 57 

Continued . . . 
iii 

TABLE OF CONTENTS (continued) 

COMMERCIALIZATION ASPECTS OF SORBENT INJECTION TECHNOLOGIES IN 

CANADA (QUARTER 8 REPORT)............................................................................................ 61 

UPCOMING EVENTS................................................................................................................. 63 

AUTHORS.................................................................................................................................... 64 

CONTACT INFORMATION....................................................................................................... 64 
iv 

LIST OF FIGURES 

1 Mercury removal as a function of ACI rate at three sites ................................................... 18 

2 Field leachate – mercury speciation.................................................................................... 38 

3 Overview of mercury flue gas interactions on an activated carbon sorbent ....................... 45 

4 Breakthrough curves for high and low acid gas.................................................................. 46 

5 Mercury and acid gas-binding mechanism at carbon edge ................................................. 47 

6 Oxidation mechanism – carbenium ion oxidant.................................................................. 48 

7 Mecury oxidation mechanism for chlorinated carbon......................................................... 49 

8 Molar relationships between mercury and selenium concentrations in seafood................. 54 

9 Molar ratio of mercury:selenium concentrations in seafood............................................... 54 

10 Molar ratio of selenium:mercury concentrations in seafood............................................... 55 

11 Relative effects of whale vs. fish consumption................................................................... 56 
v 

LIST OF TABLES 

1 CEA Mercury Program Coal Data ........................................................................................ 6 

2 CEA Mercury Program Ash Data ....................................................................................... 10 

3 CEA Mercury Program Flue Gas Data ............................................................................... 11 

4 Mercury Control Demonstration Projects Funded by the U.S. Department of Energy ...... 14 

5 Additional O&M Costs for Canadian Power Plants as a Result of Adding ACI................ 21 

6 Total Mercury in CCBs and Mercury-Leaching Results Reported by Various Groups ..... 34 

7 Summary of Field Mercury Flux Data Presented by Xin et al............................................ 39 

8 Mercury Emission from Dry-Curing Concretes.................................................................. 40 
vi 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT 

EXECUTIVE SUMMARY 

 The Canadian Electricity Association (CEA) identified a need and contracted the 

Energy & Environmental Research Center (EERC) to create and maintain an information 

clearinghouse on global research and development activities related to mercury emissions from 

coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals® (CATM®) 

Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive 

quarterly information updates that provide a detailed assessment of developments in the various 

areas of mercury monitoring, control, policy, and research. A total of eight topical reports were 

completed and are summarized and updated in this final CEA quarterly report. The original 

quarterly reports can be viewed at the CEA Web site (www.ceamercuryprogram.ca). 

 In addition to a comprehensive update of previous mercury-related topics, a review of 

results from the CEA Mercury Program is provided. Members of Canada’s coal-fired electricity 

generation sector (ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova 

Scotia Power Inc., Ontario Power Generation, SaskPower, and TransAlta) and CEA, have 

compiled an extensive database of information from stack-, coal-, and ash-sampling activities. 

Data from this effort are also available at the CEA Web site and have provided critical 

information for establishing and reviewing a mercury standard for Canada that is protective of 

environment and public health and is cost-effective. Specific goals outlined for the CEA mercury 

program included the following: 

1. Improve emission inventories and develop management options through an intensive 

 2-year coal-, ash-, and stack-sampling program 

2. Promote effective stack testing through the development of guidance material and the 

support of on-site training on the Ontario Hydro method for employees, government 

representatives, and contractors on an as-needed basis 

3. Strengthen laboratory analytical capabilities through analysis and quality assurance 

programs 

4. Create and maintain an information clearinghouse to ensure that all parties can keep 

informed on global mercury research and development activities 

 CEA members committed to a program of quarterly sampling and reporting of mercury in 

coal, residue, and stack emissions. Over the past 2 years, a large data set of approximately 

35,000 data points has been generated that characterizes the range and variability of mercury 

present in the coal and the resulting variability of mercury present in by-products and stack 

emissions. Quarterly reports from each of the member companies provide detailed data on coal 

characteristics, ash, and stack gas measurements and can be viewed at 
vii 

www.ceamercuryprogram.ca. Through this sample and analysis effort, CEA met the goal to 

improve emission inventories to support mercury management strategies (Goal 1) and provide 

member utilities experience with mercury measurement methods (Goal 2). The findings of this 

effort have helped to reduce the uncertainty around mercury emissions and concentrations in 

coal and combustion by-products and provided critical information for establishing and 

reviewing a mercury standard for Canada. 

 In conjunction with quarterly sampling, a laboratory quality assurance and quality control 

program was conducted. In general the goal of improving and validating laboratory proficiency 

in mercury analysis (Goal 3) was achieved through the laboratory round-robin. Through this 

effort, quality assurance of lab procedures and methods was achieved, and a database of coal 

characteristics from across Canada was enhanced. 

 Finally, through the compilation of this report and the previous eight quarterly Information 

Clearinghouse Reports, the goal of creating and maintaining a database of global mercury 

research has been achieved (Goal 4). 
1 

MERCURY INFORMATION CLEARINGHOUSE 

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT 

INTRODUCTION 

 The Canadian Electricity Association (CEA) identified a need and contracted the 

Energy & Environmental Research Center (EERC) to create and maintain an information 

clearinghouse on global research and development activities related to mercury emissions from 

coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals® (CATM®) 

Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive 

quarterly information updates that provide a detailed assessment of developments in the various 

areas of mercury monitoring, control, policy, and research. 

 In order to adequately address the many topics and provide the detail necessary for the 

various stakeholders to make informed decisions, selected topics were discussed in detail in each 

quarterly report. Issues related to mercury from coal-fired utilities include the general areas of 

measurement, control, policy, and transformations. Specific topics that have been addressed in 

previous quarterly reports include the following: 

• Quarterly 1 – Sorbent Control Technologies for Mercury Control 

• Quarterly 2 – Mercury Measurement 

• Quarterly 3 – Advanced and Developmental Mercury Control Technologies 

• Quarterly 4 – Rerelease of Mercury from Coal Combustion By-Products 

• Quarterly 5 – Mercury Fundamentals 

• Quarterly 6 – Mercury Control Field Demonstrations 

• Quarterly 7 – Mercury Regulations in the United States: Federal and State 

• Quarterly 8 – Commercialization Aspects of Sorbent Injection Technologies in Canada 

 In this last of nine quarterly reports, an update of these mercury issues is presented that 

includes a summary of each topic, with recent information pertinent to advances made since the 

quarterly reports were originally presented. As a result of significant advances made in some 

areas of mercury research and development, several of the updated reports contain a 

comprehensive and detailed discussion, as is the case for Quarterly 4 – Rerelease of Mercury 

from Coal Combustion By-Products, and Quarterly 3 – Advanced and Developmental Mercury 

Control Technologies. For other topics; Quarter 8– Commercialization Aspects of Sorbent 

Injection Technologies in Canada; for example, only limited new information is available and a 

brief summary of the original topical reports is provided. Each of the updated summary reports is 

provided in a section of this final Quarter 9 report. 

 In addition to a comprehensive update of previous mercury-related topics, a review of 

results from the CEA Mercury Program is provided. Members of Canada’s coal-fired electricity 

generation sector are committed to reducing mercury releases and, with CEA, have compiled an 

extensive database of information from stack-, coal-, and ash-sampling activities. Data from this 
2 

effort are available at the CEA Web site (www.ceamercuryprogram.ca) and has provided critical 

information for establishing and reviewing a mercury standard for Canada that is protective of 

environment and public health and is cost-effective. 
3 

QUARTER 9 FOCUS: MERCURY INFORMATION CLEARINGHOUSE FINAL 

REPORT 

CEA MERCURY PROGRAM OVERVIEW 

 CEA with the cooperation of eight coal-fired power generation companies in Canada 

joined forces to develop and implement the CEA Mercury Program designed to improve the 

information base around the measurement and control of mercury emissions. These utilities 

included ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia Power 

Inc. (NSPI), Ontario Power Generation (OPG), SaskPower, and TransAlta. The focus of the 

program is to improve the understanding of both human and natural sources of mercury releases, 

mercury movement through the environment, effects on human health, and the best ways to 

minimize these impacts. The coal-fired electricity generation industry is one of the largest point 

sources of mercury emissions currently and is working with governments, researchers, and other 

stakeholders to help develop effective and efficient ways of reducing these emissions. 

 The first priority of the CEA Mercury Program is to reduce the uncertainty of mercury 

measurement and emission control. The key components of the program, which have been 

ongoing for almost 3 years, include a laboratory quality assurance round-robin, research and 

development, and a mercury-sampling and analysis program. Activities continue in all of these 

areas; however, significant progress has been made, and the findings have provided critical 

information in support of the Canada-Wide Standard (CWS) for mercury from the coal-firedelectricity generating sector. 

 When the program was initiated, several goals were outlined. Through the laboratory 

round-robin, research and development, and sampling and analysis activities these goals have 

largely been met. Goals originally outlined included the following: 

1. Improve emission inventories and the development of management options through an 

intensive 2-year coal-, ash-, and stack-sampling program 

2. Promote effective stack testing through the development of guidance material and the 

support of on-site training on the Ontario Hydro method for employees, government 

representatives, and contractors on an as-needed basis 

3. Strengthen laboratory analytical capabilities through analysis and quality assurance 

programs 

4. Create and maintain an information clearinghouse to ensure that all parties can keep 

informed on global mercury research and development activities 
4 

Laboratory Quality Assurance Assessment 

 The laboratory quality assurance assessment was conducted to verify and ensure the 

accuracy and precision of mercury analysis in coal, ash, and scrubber effluent samples from 

coal-fired utilities. Proper analysis, by Canadian laboratories, of mercury in coal and ash samples 

is critical to accurately evaluate the fate of mercury across a coal-fired unit. Concentrations of 

mercury in coal, ash, scrubber effluents, and stack gas samples tend to be very low, near the 

detection limits in some cases, making consistent, reliable results difficult to achieve. To address 

these challenges, CEA member companies conducted a two-phase program. In the first phase, 

performance of 13 laboratories was assessed over a 6-month period by analyzing standard 

samples and comparing results with known values. Analysis included mercury, total chlorine, 

moisture, sulfur, total carbon (ash), and heating value (coal). Results were reviewed statistically 

to determine the laboratory’s competency to accurately analyze the parameters in specific coals 

and ashes as well as limits of quantification. According to the Mercury Laboratory Round-Robin 

Project Canadian Council of Ministers of the Environment (CCME)–CEA Project 257-2003 

Phase 1 CRM/RM Sample Report, nine of the 13 laboratories produced mercury values at least 

as good as the reference confidence limit, and “Canadian utilities produce mercury results of 

exceptional quality for coal...” (1). 

 Phase II consisted of a longer-term quality control and quality assurance effort. During 

Phase II, quarterly analysis was conducted that included reference coals and coal samples 

representative of fuel burned by Canadian utilities. Reference coal analysis provided ongoing 

measurement of laboratory performance relative to known standards. Analysis of utility coal 

samples provided valuable results from which to build a database of Canadian coal 

characteristics, which, in turn, supported the mercury emission standards development. Phase II 

of the laboratory quality assurance assessment builds upon the Coal and Ash Sampling 

Proficiency Exchange (CANSPEX) program, which was developed in 1990 to provide quality 

assurance management of coal analysis. 

 In general the goal of improving and validating laboratory proficiency in mercury analysis 

(Goal 3) was achieved through the laboratory quality assurance assessment. Through this effort, 

quality assurance of lab procedures and methods was achieved, and a database of coal 

characteristics from across Canada was enhanced. 

Mercury Research and Development 

 Significant research and technology development has been ongoing in Canada, the United 

States, and internationally. Through a variety of governmental and commercial collaborations, 

CEA member companies have been conducting research on mercury as well as other emissions 

and greenhouse gases from coal-fired boilers. 

 Through the compilation of this report and the previous eight quarterly Information 

Clearinghouse Reports, the goal of creating and maintaining a database of global mercury 

research has been achieved (Goal 4). 
5 

Mercury-Sampling and Analysis Program 

 One of the most important factors influencing mercury regulation is an accurate 

understanding of mercury fate across the process, both at specific facilities and in general for the 

coal-fired electric generating sector. In the United States, this understanding came from the 

Information Collection Request (ICR) conducted between November 1998 and July 2000. To 

support U.S. Environmental Protection Agency (EPA) regulation development, an intensive 

sampling and analysis program was undertaken to determine mercury values in coal, by-product 

effluents (bottom ash, fly ash, scrubber effluent), and stack emissions. Sampling activities were 

conducted at facilities across the United States of various emission control configurations and 

fuel types. Results from these data were compiled and helped develop a better understanding of 

how mercury behaves in these systems and to set priorities for control. 

 In Canada, the CEA Mercury Program has stated that “the first priority in managing 

mercury is to improve the inventory of mercury emissions from coal-fired power plants across 

the country” (2). In support of ongoing and historical efforts to quantify mercury emissions from 

coal-fired utilities, CEA members committed to a program of quarterly sampling and reporting 

of mercury in coal, residue, and stack emissions. Over the past 2 years, a large data set has been 

generated that characterizes the range and variability of mercury present in the coal and resulting 

variability of mercury present in by-products and stack emissions. Quarterly reports from each of 

the member companies provide detailed data on coal characteristics, ash, and stack gas 

measurements and can be viewed at www.ceamercuryprogram.ca. 

 The mercury-sampling and analysis program was designed to function in cooperation with 

the laboratory quality assurance assessment to provide accurate and precise information. The 

findings of this effort have helped to reduce the uncertainty around mercury emissions and 

concentrations in coal and combustion by-products and provided critical information for 

establishing and reviewing a mercury standard for Canada and finding cost-effective and 

efficient management options. Data generated from this sampling and analysis program have 

helped to meet CEA’s goal (Goal 1) to improve emission inventories to support mercury 

management strategies and provided member utilities experience with mercury measurement 

methods (Goal 2). A brief summary of the data compiled through this effort is provided in the 

following section. 

CEA Mercury Program Coal Data 

 The mercury emitted from coal-fired power plants, evolves directly from the mercury 

present in the coal at the time of firing. Typically, mercury is present in the coal in the tens of 

parts-per-billion range; however, it can vary significantly depending upon the type of coal and its 

source. A summary of results from sampling conducted by Canadian utilities is provided in 

Table 1 and shows that across Canada, mercury in the coal ranges from 0.007–0.640 mg/kg 

(ppm), with typical concentrations around 0.05–0.09 mg/kg. The data presented in Table 1 

comprise average coal characteristics from sampling activities conducted at several collaborating 

CEA member companies. In general, the data are a compilation of many coal analyses conducted 
6 

 Table 1. CEA Mercury Program Coal Data 

Power Plant MW Coal Type 

Blend 

Ratio 

Moisture, 

% 

Ash, 

% (dry) 

Mercury, 

mg/kg (dry) 

Mercury, 

Min/Max, mg/kg1

Chlorid

mg/kg (d

ATCO Power Battle River – 5 375 sub-b. NA 24.56 16.81 0.040 0.023/0.063 28 Sheerness – 1 and 2 767 sub-b. NA 24.59 18.53 0.060 0.034/0.089 29 EPCOR Power Genesee – 1 and 2 820 sub-b. NA 18.57 21.62 0.043 0.029/0.066 105 Manitoba Hydro Brandon GS – 5 105 sub-b. NA 10.83 6.28 0.077 0.032/0.172 18 New Brunswick Power Belledune 490 bit. NA 11.08 10.11 0.044 0.018/0.095 245 NSPI Lingan – 1 and 2 300 petc./bit. 21/79 10.94 7.36 0.053 0.023/0.160 378 Lingan – 3 and 4 300 petc./bit. 21/79 10.94 7.36 0.053 0.023/0.160 378 Point Aconi – 1 165 petc./bit. 75/25 7.83 2.75 0.023 0.007/0.071 294 Point Tupper 150 petc./bit. 18/82 10.65 6.20 0.047 0.012/0.114 297 Trenton – 5 150 petc./bit. 4/96 8.13 8.39 0.100 0.035/0.195 816 Trenton – 6 160 petc./bit. 26/74 6.57 17.93 0.039 0.012/0.087 756 OPG Atikokan 215 lig NA 34.19 15.26 0.089 0.060/0.136 25 Lambton – 1 and 2 1000 bit. NA 8.72 9.24 0.063 0.018/0.640 641 Lambton – 3 and 4 505 each bit. NA 6.75 8.44 0.096 0.063/0.322 861 Nanticoke – 5, 6, and 7 500 each sub-b./bit. 70/30 21.83 7.93 0.066 0.039/0.102 471 

Thunder Bay – 2 and 3 310 lig./sub-b. 80/20 31.02 12.39 0.084 0.010/0.310 17 TAU Sundance – 5 and 6 760 sub-b. NA 19.14 20.92 0.069 0.040/0.100 70 SaskPower2

Boundary Dam – 1 66 lig. NA 32.72 13.54 0.073 0.055/0.098 10 Boundary Dam – 2 66 lig. NA 32.91 13.45 0.072 0.055/0.097 10 Boundary Dam – 3 150 lig. NA 32.82 13.53 0.073 0.053/0.098 10 Boundary Dam – 4 150 lig. NA 32.39 13.62 0.075 0.055/0.098 10 Boundary Dam – 5 150 lig. NA 32.37 13.70 0.076 0.052/0.109 10 Boundary Dam – 6 300 lig. NA 32.44 13.72 0.073 0.052/0.093 10 Poplar River – 1 300 lig NA 36.84 13.69 0.090 0.068/0.114 12 Poplar River – 2 300 lig. NA 36.83 13.72 0.089 0.068/0.114 12 Shand 305 lig. NA 31.97 13.88 0.078 0.044/0.119 9 Note: bit.=bituminous, sub-b.=sub-bituminous, lig.=lignite, petc.=petcoke 

1 Quarterly Data Reports 2 SaskPower coal and ash results are as-received, not dry basis. 
7 

since the effort began in the fall of 2002, with the maximum and minimum mercury and chlorine 

values presented to illustrate the range across Canadian fuels. 

 Based on the mercury data presented in Table 1, it is clear that variability exists both 

among the various power plants and within coal samples from a single facility. It is reasonable to 

expect similar relative variability in stack emissions, with additional variability due to the range 

of effectiveness of electrostatic precipitators (ESPs), fabric filters (FFs), and flue gas 

desulfurization (FGD) units at capturing mercury. 

CEA Mercury Program Ash Data 

 Mercury present in the coal is volatilized during combustion and exits the boiler with the 

flue gas. As the gas cools in the preheater and ductwork, opportunities for the mercury to react or 

adsorb to other constituents in the flue gas exist. One pathway by which mercury finds its way 

out of the flue gas is by adsorbing to fly ash. Typically, ash with relatively high levels of 

unburned carbon exhibit the highest mercury concentration. Particulate control devices, 

therefore, become mechanisms for mercury capture depending upon the flue gas characteristics, 

ash composition, and operating conditions. Typically, mercury is not found in large quantities in 

bottom ash because of the high temperature in the boiler. This is consistent with data collected 

from Canadian utilities and presented in Table 2. The concentration of mercury in bottom ash 

ranged from less than 0.003 to 0.228 mg/kg; however, the average value was 0.02 mg/kg. 

 Mercury present in fly ash was typically one or two orders of magnitude higher than 

measured in the bottom ash. The concentration of mercury in the fly ash ranged from less than 

0.003–0.847 mg/kg. Several plants, including OPG’s Nanticoke Units 5–7 and Lambton 

Units 1–4, had the highest mercury concentration in the ash. At Nanticoke Units 5–7, high levels 

of mercury in the fly ash, 0.637, could be related to the higher chloride concentration of the fuel. 

Table 1 shows an average chloride concentration for these fuels of 471 mg/kg for 

Units 5, 6, and 7. At chloride levels in the mid-100s, higher mercury concentrations are 

sometimes observed in the ash. Based on the present understanding of mercury fundamentals, it 

is believed that the presence of halogens in the flue gas improves the adsorption of mercury to 

carbon and/or ash, resulting in greater mercury capture and higher concentrations in hopper ash. 

This is consistent with the high carbon content measured in the ash at all of the Nanticoke and 

Lambton Units. 

 At Lambton Units 1 and 2 and Units 3 and 4 the percentage of carbon exceeded 10%, 

similar to fly ash at Nanticoke. This high carbon content coupled with coal chloride greater than 

500 ppm (Table 1) likely contributed to the higher-than-average mercury concentration 

measured in the fly ash. At Lambton 1 and 2, the average fly ash concentration was 0.326 mg/kg 

and at Lambton 3 and 4 0.274 mg/kg, nearly twice the level measured from the next highest unit. 
8 

CEA Mercury Program Flue Gas Data 

 Stack sampling was generally conducted by either Ontario Hydro method or EPA Method 

29 (multimetal sampling method) to quantify mercury emissions from the stacks of several 

Canadian utilities. Results from these tests in terms of emission rate in grams/hour and, in some 

cases, speciated mercury concentration are summarized in Table 3. In general, the values 

presented are an average of triplicate sampling (not necessarily representative of overall annual 

emissions), and the emission rate represents the estimated mercury emission from each unit. For 

those facilities that list two units, flue gas is exhausted through a common stack and the emission 

rate represents the mercury emission from the two units combined. 

 The stack gas mercury measurements conducted for the CEA Mercury Program typically 

represent snapshots of emission rates and have not been conducted over long enough periods to 

fully characterize emissions. However, they do provide useful information when reviewed 

relative to coal and ash results. The coal and ash data presented in Table 3 differ from the values 

presented in Tables 1 and 2 in that Table 3 data correspond only with coal and ash data collected 

during stack test activities. The two factors influencing stack mercury concentrations and 

emissions are the mercury content in the fuel and subsequent removal via pollution control 

devices. The mercury concentrations measured from CEA utilities range from 0.32 to 

22.05 μg/Rm3

. NSPI’s Point Aconi (only continuous fluidized-bed combustor tested) measured a 

stack gas mercury concentration of 0.32 μg/Rm3 (one of the lowest measured) and, showed a 

relatively high mercury content in the ash, indicating that significant mercury capture is 

occurring across the FF. A similarly low stack mercury concentration was measured at OPG’s 

Lambton Unit 4, indicating mercury capture is occurring across the ESP and/or FGD. 

 The highest mercury concentrations measured at the stack were at SaskPower’s Poplar 

River, Boundary Dam, and Shand facilities, where the concentration was greater than 

10 μg/Rm3 from each of the five stacks tested. Speciation data from each of these three stacks 

show an elemental mercury fraction greater than 70%, consistent with lignite fuels. Coal data 

from these plants during stack sampling show mercury concentrations typically between 0.05 

and 0.10 mg/kg and typically low chloride concentrations, 15 mg/kg. Based on these 

characteristics, it is not surprising that very little mercury was measured in the ESP ash and 

emission rates are higher than at other units. 

 The predominant emission control for Canadian utilities is a cold-side ESP, with the 

exception of Point Aconi, which has a FF. The other units that are unique among those tested 

include New Brunswick Power’s Belledune, which operates an ESP and FGD and OPG’s 

Lambton Unit 4 which has SCR, a C-ESP and FGD. Ash data from Belledune suggest that a 

significant amount of mercury is not captured by the ESP. However, the stack mercury 

concentration (1.08–1.2 μg/Rm3

) is lower than most of the units tested and suggests that some 

mercury capture is occurring across the FGD similar to Lambton Unit 4. 
9 

Mercury Policy 

 The Government of Canada, working closely with provincial and territorial partners, has 

accepted in principle a draft of the CWS for mercury emissions from coal-fired power plants 

(www.ccme.ca/initiatives/standards.html). Later this year, the draft will be reviewed by the Air 

Management Committee, Environmental Planning and Protection Committee, and Deputy 

Ministers Committee, and a finalized version will be developed. The final CWS is expected to be 

endorsed by the CCME in the first half of 2006. According to John Mayes, Assistant Director of 

the Standards Development Branch at the Ontario Ministry of the Environment at Air Quality V, 

the primary goals for the standard were (3): 

• Develop a CWS by 2005 

• Explore national capture of 60% to 90% of mercury 

• Provide for mercury emission reductions by 2010 

• Align with U.S. standards for mercury 

 The first three of these goals are being met. In accordance with provincial caps provided 

for under the draft CWS, mercury emissions would be reduced from the current 2695 kg/yr to 

1130 kg/yr (58% reduction) by 2010 based on best achievable control technology economically 

available (BATEA). Therefore, the coal-fired utilities will need to install mercury technologies 

that can provide 50%–60% control. In addition, as part of the CWS, a review process will be 

implemented to evaluate requiring much higher levels of control, up to 80% by 2018. For new 

facilities, the use of best available control technologies (BACT) for mercury will be required 

upon start-up. Based on current estimates, BACT levels would be 85% control for bituminous 

coals and blends (emission rates of 3 kg/TWh) and 75% control for lignites (15 kg/TWh) and 

subbituminous fuel (8 kg/TWh).

 The reporting and measurement protocols for the CWS have not yet been issued. Based on 

a recent conversation with Don Rose of Environment Canada, it is expected that these will be 

issued in early spring of 2006. 

 Based on the draft, the CWS will require a higher level of mercury control from power 

plants and in a shorter time frame than the EPA Clean Air Mercury Rule (CAMR). However, by 

2018, the CAMR and CWS will be similar. Although trading will be allowed under CAMR, it is 

not part of the draft CWS. 

 In March 2005, EPA issued the first-ever mercury regulation titled the CAMR. At Air 

Quality V, Robert Weyland of EPA said the rationale for the rule was EPA’s desire to allow 

electric generating utilities as much flexibility as possible and still protect public health (4). As a 

result, EPA issued the rule under Section 111 rather than Section 112 of the Clean Air Act 

Amendment (CAAA), thereby providing a cap-and-trade mechanism. The rule is designed to be 

implemented in two phases. The first phase would cap mercury emissions from coal-fired power 

plants at 38 tons/year by 2010 (about 48 tons/year is currently being emitted) and the second 

phase would permanently cap emissions at 15 tons/year by 2018. It is EPA’s position that the 

first phase will be accomplished as a cobenefit of the February 2005 Clean Air Interstate Rule 
10 

Table 2. CEA Mercury Program Ash Data 

BOTTOM ASH ANALYSIS 

Power Plant MW Coal Type 

Blend 

Ratio 

Bottom Ash: 

Fly Ash Ratio 

Moisture,

% 

Carbon, % 

(dry) 

Mercury1, 

mg/kg (dry) 

Mercury, 

Min/Max. 

mg/kg* 

Moisture, 

% 

ATCO Power Battle River – 5 375 sub-b. NA 40:60 0.42 0.27 0.006 <0.003/0.011 0.01 

Sheerness – 1 and 2 767 sub-b. NA 40:60 0.46 1.77 0.006 <0.003/0.031 0.04 

EPCOR Power Genesee – 1 and 2 820 sub-b. NA 40:60 0.12 2.21 0.003 <0.003/0.005 0.22 Manitoba Hydro Brandon GS – 5 105 sub-b. NA 25:75 0.410 0.524 0.029 <0.003/0.102 0.219 New Brunswick Power Belledune 490 bit. NA 20:80 - - 0.021 0.0010/0.076 0.12 NSPI Lingan – 1 and 2 300 petc./bit. 21/79 15:85 0.29 - 0.002 <0.003 0.42 Lingan – 3 and 4 300 petc./bit. 21/79 15:85 0.29 - 0.002 <0.003 0.42 Point Aconi – 1 165 petc./bit. 75/25 47:53 0.25 - 0.080 0.074/0.086 0.31 Point Tupper 150 petc./bit. 18/82 18:82 0.58 - 0.012 0.009/0.015 0.36 Trenton – 5 150 petc./bit. 4/96 10:90 0.25 - 0.002 <0.003 0.36 Trenton – 6 160 petc./bit. 26/74 10:90 0.28 - 0.003 <0.003/0.007 0.31 OPG Atikokan 215 lig. NA 20:80 0.07 0.17 0.0034 <0.003/0.053 0.04 Lambton – 1 and 2 1000 bit. NA 15:85 - - 0.053 0.020/0.116 10.24 Lambton – 3 and 4 505 each bit. NA 15:85 0.20 10.69 0.119 0.031/0.228 10.43 Nanticoke – 5, 6, and 7 500 each sub-b./bit. 70/30 15:85 0.30 8.89 0.019 0.014/0.022 0.16 Thunder Bay – 2 and 3 310 lig./sub-b. 80/20 25:75 0.055 0.60 0.063 <0.003/0.342 0.16 TAU Sundance – 5 and 6 760 sub-b. NA 40:60 0.73 5.24 0.014 0.008/0.020 0.22 SaskPower Boundary Dam – 1 66 lig. NA 20:80 0.15 2.24 0.013 ND/0.081 0.04 Boundary Dam – 2 66 lig. NA 20:80 0.73 14.46 0.009 ND/0.037 0.07 Boundary Dam – 3 150 lig. NA 20:80 0.19 1.72 0.011 ND/0.060 0.08 Boundary Dam – 4 150 lig. NA 20:80 0.37 13.44 0.072 0.012/0.195 0.05 Boundary Dam – 5 150 lig. NA 20:80 0.13 3.01 0.061 <0.001/0.214 0.12 Boundary Dam – 6 300 lig. NA 20:80 0.32 3.50 0.003 <0.001/0.006 0.03 Poplar River – 1 300 lig NA 20:80 0.17 1.08 0.003 0.001/0.010 0.09 Poplar River – 2 300 lig. NA 20:80 0.13 1.06 0.003 ND/0.005 0.07 Shand – A Side 305 lig. NA 20:80 0.13 0.93 0.004 ND/0.034 0.09 Shand – B Side 0.06 Note: bit.=bituminous, sub-b.=sub-bituminous, lig.=lignite, petc.=petcoke 

*Quarterly Data Reports 1 Where average Hg concentration is below the lower limit of quantification (LoQ), 1⁄2 of the LoQ was reported. 
11 

Table 3. CEA Mercury Program Flue Gas Data Total Hg Emissions SpeciatioPower Plant MW/Coal Type 

Method 

Used 

Coal 

Mercury, 

mg/kg (dry) 

Bottom Ash 

Mercury, 

mg/kg (dry) 

Fly Ash 

Mercury, 

mg/kg (dry) 

Concentration, 

μg/Rm^3 

Emission 

Rate, g/h 

Particulate, 

% 

ATCO Power Battle River – 5 375 Sub-b M-291 0.039 0.004 0.060 4.66 dry 8.05 <1 

Sheerness – 1 and 2 767 Sub-b M-291 0.060 0.002 0.042 3.35 dry 10.33 <1 EPCOR Power Genesee – 1 and 2 

820 Sub-b M-29 (2), 

OH (1)2 0.043 0.003 0.133 3.25-6.43 7.88-20.66 <1 

Manitoba Hydro Brandon GS – 5 105 Sub-b OH 0.050 <0.003 0.150 3.76-6.38 2.05-2.56 <1 New Brunswick Power 

Belledune 490 Bit. OH 0.033 0.010 0.059 1.08-1.20 2.03-2.16 2–5 

NSPI Lingan – 1 and 2 300 Petc/Bit OH 0.058 <0.003 0.014 4.82 5.82 1 

Lingan – 3 and 4 300 Petc/Bit OH 0.1275 0.002 0.018 - 12.52 - 

Point Aconi – 1 165 Petc/Bit OH 0.032 0.003 0.149 0.32 0.23 4 

Point Tupper 150 Petc/Bit OH 0.062 0.094 0.016 5.24 3.60 <1 

Trenton – 5 150 Petc/Bit OH 0.093 <0.003 0.069 7.02 4.33 1 

Trenton – 6 160 Petc/Bit OH 0.046 0.004 0.050 3.71 2.28 1 

OPG Lambton – 43 505 Bit. OH 0.095 0.051 0.226 0.36 0.76 1 

Nanticoke – 5 500 Sub-b/Bit OH 0.0643 0.009 0.562 2.73 10.58 1 Nanticoke – 6 500 Sub-b/Bit OH 0.0703 0.010 0.899 2.50 14.70 <1 Nanticoke – 7 500 Sub-b/Bit OH 0.0607 0.016 0.721 3.32 13.86 4 TAU 

Sundance – 5 and 6 760 Sub-b OH 0.056 0.010 0.146 3.27 10.09 0 

SaskPower 

Boundary Dam – 1 and 24 132 Lig. OH 0.073 0.008 0.080 17.68 (3% O2 dry) 11.45 <1 

Boundary Dam – 54 150 Lig. OH 0.090 - 0.037 19.39 (3% O2 dry) 12.13 <1 Boundary Dam – 6 150 Lig. OH 0.052 0.002 0.098 14.00 (6% O2 dry) 14.30 2 Poplar River – 1 

300 Lig. 

OH 0.099 0.006 0.072 

22.05 (7.7% O2

dry) 20.70 0 

Shand – 1 300 Lig. OH 0.052 0.002 0.056 11.8 (6% O2 dry) 14.08 <1 

N/A = not applicable 1 Results from 1999 OH tests. 2 Average of two Method 29 and one OH test, speciation data from EERC. 3 Data from September 10–12, 2003, test. 4 Average of two tests (1-EERC, 1-SaskPower); speciation data from EERC. 
12 

(CAIR), which requires that a number of utilities in the eastern states install wet FGD systems 

for SO2 control and selective catalytic reduction (SCR) for NOx control. Mitchell Baer of DOE 

added that, although the second phase of the rule will require addition mercury controls, it is 

expected that a number of mature economical technologies will be available to meet CAMR 

requirements (5). 

 As presented in Quarter 7 – Mercury Regulations in the United States: Federal and State, 

CAMR has been controversial, and 11 states and four environmental groups have filed suit. Of 

particular concern to the states and organizations is the delisting of mercury from Section 112 of 

the CAAA which provides for maximum achievable control technology and the decision to 

regulate mercury under Section 111, providing for a cap-and-trade structure. At the same time, 

these lawsuits were filed, petitions for reconsideration were sent to the EPA administrator. The 

petitions requested EPA reconsider both CAMR and the legality of delisting utilities from 

Section 112 of the CAAA to Section 111. There were four petitions asking reconsideration of the 

delisting. One petition was submitted by 14 states: New Jersey, California, Connecticut, 

Delaware, Illinois, Maine, Massachusetts, New Hampshire, New Mexico, New York, 

Pennsylvania, Rhode Island, Vermont, and Wisconsin. The second petition was submitted by 

five environmental groups: The Natural Resources Defense Council, the Clean Air Task Force, 

the Ohio Environmental Council, the U.S. Public Interest Research Group, and the Natural 

Resources Council of Maine. The two other petitions received by the EPA were from the 

Jamestown Board of Public Utilities and the Integrated Waste Service Association. Two 

petitions were received to reconsider the methodology of CAMR in determining caps and NSPS. 

One petition was received from the same 14 states and the other from five environmental groups 

and four Indian tribes. As a result, the EPA elected to reconsider on June 24, 2005, by asking for 

public comment. However, the reconsideration process will not stay the rule. 

References 

1. www.ceamercuryprogram.ca/EN/Pdf/CCME%20257-2003%20CRM%20RM%20Report% 

 20Final%2026%20March%202003.pdf (accessed Dec 2005). 

2. www.ceamercuryprogram.ca/EN/I-Plan/IPlan_All.pdf (accessed Dec 2005) 

3. Mayes, J. Canada-Wide Standard for Mercury Emissions for Coal-Fired Electric Power 

Generation Plants. Presented at the Air Quality V: Mercury, Trace Elements, SO3, and 

Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005. 

4. Wayland, R.J. Clean Air Mercury Rule (CAMR). Presented at the Air Quality V: Mercury, 

Trace Elements, SO3, and Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005. 

5. Baer, M. Technical and Policy Issues Associated with Hg Control Technologies for CAMR 

and CAIR, DOE Role and Perspective. Presented at the Air Quality V: Mercury, Trace 

Elements, SO3, and Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005. 
13 

SORBENT CONTROL TECHNOLOGIES FOR MERCURY CONTROL AND 

MERCURY CONTROL FIELD DEMONSTRATIONS (QUARTER 1 AND QUARTER 6 

REPORTS) 

Field Demonstrations of Carbon Injection 

In 1999, the DOE National Energy Technology Laboratory (NETL) issued a request for 

proposal (RFP) to test mercury control technologies at full scale. The near-term goal of the RFP 

was to evaluate technologies that could achieve 50%–70% mercury removal at a cost of less than 

three-quarters of the estimated cost of $50,000–$70,000/lb (CAN$136,000–CAN$191,000/kg) 

mercury removed. The longer-term goal was to develop technologies that could provide up to 

90% control at a cost of half to three-quarters of activated carbon injection technology by the 

year 2010. During 2003 and 2004, NETL issued three more RFPs to evaluate mercury control 

technologies through its Office of Fossil Energy’s Innovation Program and through the Clean 

Coal Initiative. In 2005, they issued the Phase III RFP to demonstrate control technologies on a 

longer-term basis that can obtain 90% mercury control. In addition, pilot-scale tests for more 

novel technologies were encouraged, as well as new techniques for cleaning coal that can 

remove mercury. It is expected that awards will be made in early spring of 2006. 

 In September 2005, at Air Quality V: International Conference on Mercury, Trace 

Elements, SO3, and Particulate Matter, Tom Feeley of DOE–NETL presented an update 

regarding the status of mercury control programs (1). It is clear that significant strides have been 

made in developing effective mercury control technology over the past several years, particularly 

for low-rank coals. Based on the status of the Phase II program, Tom Feeley concluded the 

following: 

• Activated carbon/sorbent injection and oxidation systems (i.e., catalysts, chemical 

additives) are the most promising Hg control technologies. 

• The estimated cost of mercury control on a $/lb-removed basis has been significantly 

reduced. 

• DOE’s current field testing activity is a research and development (R&D) program and, 

therefore, further long-term field testing is needed to bring technology to commercial 

demonstration readiness. 

• DOE’s research, development, and demonstration (RD&D) model projects broad 

commercial availability of mercury control technologies in the 2012–2015 time frame. 

• The fate of mercury in combustion and gasification by-products remains an issue. 

 Table 4 summarizes 42 large-scale mercury control projects. This information identifies 

the lead contractor for each project, the demonstration site, boiler type and size, fuel type, air 

pollution control device (APCD) employed, mercury control technology being evaluated, and 

project status. The demonstration sites represent utility boilers across the United States and one 
14 

Table 4 .Mercury Control Demonstration Projects Funded by the U.S. Department of Energy Lead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg CoUND EERC Leland Olds Station Unit 1 

Basin Electric Power Cooperative 

B&W wall-fired 220 MW 

ND lignite c-ESP ACI w

ADA-ES Inc. Coal Creek Station Unit 1 

Great River Energy 

CE t-fired 546 MW 

ND lignite c-ESP 

Wet FGD 

TOXE

B&W Endicott Station 

Michigan South Central Power Agency 

B&W Stirling boiler 55 MW 

Bituminous c-ESP 

Wet FGD 

FGD r

B&W Zimmer Station 

Cinergy 

B&W Carolina boiler 1300 MW 

Bituminous c-ESP 

Wet FGD 

FGD r

Mobotec USA Cape Fear Station Unit 5 

Progress Energy 

CE t-fired 154 MW 

Low-sulfur bituminous 

c-ESP Sorben

ROFA

Southern Company E.C. Gaston Station Unit 3 

Alabama Power 

CE t-fired 270 MW 

Low-sulfur bituminous 

h-ESP COHPACTM 

ACI 

URS Plant Yates Unit 1 

Georgia Power 

CE t-fired 100 MW 

Low-sulfur bituminous 

c-ESP ACI 

URS Plant Yates Unit 2 

Georgia Power 

CE t-fired 100 MW 

Low-sulfur bituminous 

c-ESP Wet FGD 

ACI 

Sorbent Technologies Corporation 

St. Clair Station Unit 1 DTE Energy 

B&W wall-fired 160 MW 

PRB PRB–bit. blend 

c-ESP Bromin

Sorbent Technologies Corporation 

Buck Station Duke Energy 

NA Low-sulfur 

bituminous 

h-ESP Bromin

ADA-ES Inc. Holcomb Station 

Sunflower Electric Power Corporation 

B&W Carolina Boiler 360 MW 

PRB PRB–W-bit. 

SDA–FF ACI 

Coal b

URS Stanton Station Unit 1 

Great River Energy 

FW wall-fired 150 MW 

PRB c-ESP ACI 

URS Stanton Station Unit 10 

Great River Energy 

CE t-fired 60 MW 

ND lignite SDA–FF ACI 

SaskPower and UND EERC 

Poplar River Power Station Units 1 and 2 SaskPower 

NA 300 MW 

Poplar River lignite 

c-ESP ACI 

Pilot-s

ADA-ES Inc. Meramec Station 

AmerenEU 

NA 140 MW 

PRB c-ESP ACI 

UND EERC Stanton Station Unit 1 

Great River Energy 

FW wall-fired 150 MW 

PRB c-ESP ACI 

UND EERC Antelope Valley Station Unit 1 

Basin Electric Power Cooperative 

CE t-fired 440 MW 

ND lignite SDA–FF ACI 

ACI w

 
15 

Table 4. Mercury Control Demonstration Projects Funded by the U.S. Department of Energy (continued)Lead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg ConUND EERC Milton R. Young Station Unit 2 

Minnkota Power Cooperative 

B&W cyclonefired 450 MW ND lignite c-ESP Wet FGD Mercury 

fuel/FG 

UND EERC Monticello Station Unit 3 

Texas Utilities Company 

B&W wall-fired 750 MW 

Texas lignite c-ESP 

Wet FGD 

Mercury fuel/FG 

UND EERC Big Brown Station 

Texas Utilities Company 

CE t-fired 600 MW 

Texas lignite Lignite–PRB 

c-ESP ACI 

URS Monticello Station Unit 3 

Texas Utilities Company 

B&W wall-fired 750 MW 

Texas lignite c-ESP 

Wet FGD 

Wet FG

URS Plant Yates Unit 2 

Georgia Power 

CE t-fired 100 MW 

Low-sulfur bituminous 

c-ESP Wet FGD 

Wet FG

URS Conesville Station 

American Electric Power 

NA 400 MW 

Bituminous c-ESP 

Wet FGD 

Wet FG

ADA-ES Inc. Conesville Station 

American Electric Power 

NA 400 MW 

Bituminous c-ESP 

Wet FGD 

ACI 

ADA-ES Inc. Laramie River Station Unit 3 

Missouri Basin Power Project 

B&W 550 MW 

PRB SDA–ESP ACI 

ADA-ES Inc. Monroe Station Unit 4 

Detroit Edison 

B&W 785 MW 

PRB–bit. blend c-ESP ACI 

ADA-ES Inc. Louisa Station Unit 1 

MidAmerican 

B&W 650 MW 

PRB h-ESP Sorbent 

ADA-ES Inc. Independence Station Unit 1 

Entergy 

CE 840 MW 

PRB c-ESP TOXEC

ADA-ES Inc. Gavin Station 

American Electric Power 

B&W 1300 MW 

Bituminous c-ESP TOXEC

ADA-ES Inc. Council Bluff Unit 2 

MidAmerican 

NA PRB h-ESP Sorbent 

ALSTOM Power, Inc. Dave Johnston Station 

PacificCorp 

NA PRB c-ESP ACI wit

ALSTOM Power, Inc. Leland Olds Station Unit 1 

Basin Electric Power Cooperative 

B&W 440 MW 

ND lignite c-ESP ACI wit

ALSTOM Power, Inc. Portland Station 

Reliant Energy 

NA Bituminous c-ESP ACI wit

GE EER John Sevier Station 

Tennessee Valley Authority 

NA Bituminous NA Combin

NOx Co

 
16 

Table 4. Mercury Control Demonstration Projects Funded by the U.S. Department of Energy (continued)Lead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg ConSouthern Company Daniel Station Unit 1 CE t-fired 

540 MW 

60–40 Blend PRB–Bit. 

c-ESP ACI and 

ACI 

GE EER Lee Station Unit 3 

Progress Energy 

NA Bituminous c-ESP Combin

NOx con

Sorbent Technologies Corporation 

Lee Station Unit 1 Progress Energy 

NA Bituminous c-ESP Bromin

Sorbent Technologies Corporation 

Crawford Station Unit 7 Midwest Generation 

NA PRB c-ESP Bromin

Sorbent Technologies Corporation 

Will County Station Midwest Generation 

NA PRB h-ESP Bromin

Mobotec USA Whitewater Station 

Richmond Power and Light 

NA NA NA Sorbent 

ROFATM

ADA-ES Inc. Presque Isle Station 

WE Energy 

NA NA NA TOXEC

Amended Silicates, LLC Miami Fort Station Unit 6 

Cinergy 

NA 175 MW 

Bituminous c-ESP Amende

ACI – activated carbon injection ADA-ES Inc. – ADA Environmental Solutions Inc. B&W – Babcock & Wilcox CE – Combustion Engineering COHPAC – compact hybrid particulate collector c-ESP – cold-side electrostFGD – flue gas desulfurization FW – Foster Wheeler GE EER – GE Energy and h-ESP – hot-side electrostatic precipitator NA – not available PRB – Powder River Basin ROFATM – Rotating Opposed-Fire Air ROTAMIXTM – Rotating Mixing SDA–FF – spray dryer abso

SEA – sorbent enhancement additive TBD – to be determined t-fired – tangentially fired UND EERC – University of North Dakota URS – URS W-bit. – western bituminou Energy & Environmental Research Center 
17 

in Canada. Boiler types representing the major North American boiler manufacturers are 

included. Fuel types represented include U.S. northern plains and Gulf Coast lignite, PRB 

subbituminous coal, high- and low-sulfur bituminous coal, and Canadian lignite. Air pollution 

control technologies represented include c-ESPs and h-ESPs, various types of wet FGD systems, 

and SDA–FFs. All of these projects involve the evaluation of some type of additive, reagent, or 

sorbent for its potential to control Hg emissions in conjunction with existing air pollution control 

technology or modify Hg speciation in the flue gas to facilitate Hg control. 

 Most of these tests were previously reported in “CEA Quarter 6 – Mercury Control Field 

Demonstrations”; therefore, this report will only summarize the key findings and provide 

reported results for those tests completed recently. Although several projects have been 

completed, most projects are ongoing, with a significant number scheduled to begin in 2006. 

 The use of sorbent injection and/or ACI as a means of removing mercury from coal 

combustion flue gas is widely accepted as the most developed and commercially viable 

alternative. Many other technologies are being investigated, but the demonstrated performance 

of activated carbon in pilot- and full-scale tests make it the leading candidate for achieving the 

goals of the draft CWS for mercury emissions from coal-fired power plants. Although, ACI is 

considered the most promising and, therefore, the most tested technology option, it should be 

recognized that not all plant configurations or fuels have been tested to the same degree and 

additional data are needed to minimize uncertainty and ensure commercial readiness. Clearly, 

whether ACI is considered a commercially available technology by all groups depends on the level 

of testing that has been performed thus far and the confidence that the providers (vendors) and 

buyers (utilities) have in these data. Recent comments by the Institute of Clean Air Companies 

(ICAC) state that “companies are providing firm price proposals with performance guarantees for 

every coal and boiler type (2).” However, at the time of this review, there were no guarantees in 

place at plants in Canada. The President of ADA-ES was recently quoted as saying, “We can take 

an order for design and install, and a utility could be reducing mercury within six months.” Based 

on comments that were submitted to EPA prior to the CAMR being announced, utilities and coal 

suppliers dispute vendors’ ability to make performance guarantees and emphasize that additional 

testing is needed (3). 

 There are a number of major producers of powdered activated carbon (PAC) in the United 

States, Canada, Europe, and China, including the following: 

• Norit Americas 

• Calgon 

• Nucon International 

• Luscar, Ltd. 

• Barnebey and Sutcliffe Corporation 

• RWE Rheinbraun 

• Ningxia Huahui 
18 

 With a few exceptions, most of the testing has been done with Norit Americas DARCOTM

HG (formerly called DARCOTM FGD). However, in practice the carbons have provided similar 

results and have an average cost of about $0.50/lb. 

 Results from full-scale tests using ACI at three sites are shown in Figure 1. As was expected, 

the use of a FF (high air-to-cloth ratio, COHPACTM) with ACI at the E.C. Gaston Station 

provided the best mercury removal at the lowest ACI rate, 87%–90% removal at an ACI rate of 

1.5 lb/Macf. However, as a result of increased particulate loading to the COHPACTM, the 

cleaning frequency increased significantly. At Brayton Point Station (ESP alone), burning a 

similar coal (low-sulfur bituminous), an ACI rate of 20 lb/Macf was needed to obtain 90% 

mercury removal. At an ACI rate of 1.5 lb/Macf, only about 15% mercury removal was achieved 

at the Brayton Point Station. 

 Testing at Pleasant Prairie Station using PRB coal and a c-ESP, resulted in a maximum 

mercury removal of 66% regardless of the ACI rate. However, at an ACI rate of 1.5 lb/Macf, 

mercury removal was ~40%. EERC pilot-scale tests showed relatively low mercury capture when 

Fort Union lignite was fired with an ESP only. Mercury removal of only 45% was achieved even at 

a high ACI rate of 20 lb/Macf (4). 

 In general, the results shown in Figure 1 are representative of results achieved at many 

sites. For example a full-scale evaluation of ACI at the Yates plant, was conducted by URS 

Corporation working with Southern Company (5). The test unit fires an eastern bituminous coal 

and has a small ESP (SCA of 173 ft2

/kacfm). Results showed that 60%–70% removal is 

achievable at 4.5 lb/MMacf, improving to 70%–80% at 6.5 lb/MMacf, with no further 

improvement at the higher injection rate. In addition to demonstrating mercury removal, another 

purpose for the test was to determine the effects of ACI on ESP performance. At low loads there 

Figure 1. Mercury removal as a function of ACI rate at three sites. 
19 

did appear to be increased arcing across the ESP. However, longer-term tests need to be 

completed before final conclusions can be made. 

 Another test recently completed evaluating ACI for a PRB coal was conducted by a team 

led by ADA-ES (6). Sites tested included Holcomb, Laramie River, Meramec, and Monroe 

Power Plants. The first three sites fired 100% PRB coal, and the fourth, Monroe, uses a 60–40 

blend of PRB–eastern bituminous coal. The emission control configuration was unique for each 

of the units tested. Holcomb has a SDA–FF, Laramie River a SDA–ESP combination, Meramec 

only an ESP, and the Monroe plant an SCR followed by an ESP. Mercury removal at Meramec 

and Laramie River gave results similar to those presented in Figure 1 for Pleasant Prairie. At 

these plants, the percent mercury removal reaches a maximum and then flattens out, and there is 

little or no improvement regardless of the amount of carbon added. For Meramec the maximum 

mercury removal was about 75% at an ACI rate of 5 lb/MMacf; at Laramie River, the maximum 

was only 45% at the same ACI rate. It is likely that the lower removal at Laramie River was a 

result of the SDA removing the chloride. However, very different results were obtained at 

Monroe and Holcomb. At Monroe, which blends eastern bituminous coal with PRB, over 90% 

mercury removal was achieved at an ACI rate of 5 lb/MMacf, with similar results at Holcomb, 

90% removal of mercury at an ACI rate of 6 lb/MMacf. 

Field Demonstrations Using Chemically Treated Carbons 

It has been determined, based on bench- and pilot-scale tests, that a limiting factor for 

western fuels is the relatively low level of chlorides in the coal compared to eastern bituminous 

coals. Therefore, one method to improve ACI performance is to treat the carbon with a halogen, 

chlorine, bromine, or iodine. The primary focus for many of the Phase II field demonstration 

projects was to use these halogenated carbons to achieve higher levels of mercury control. For 

example, Sorbent Technologies has developed brominated powered activated carbons (B-PACs) 

that have proven very effective at removing mercury at a variety of power plants (7). Some 

plants have achieved >90% mercury removal at a cost that is <50% of DOE’s baseline estimate. 

Based on this and other work, it appears that halogenated carbons can improve mercury capture 

for low-chloride coals but provide less benefit for eastern fuels. 

 In similar testing led by URS Corporation, a Darco-Hg LHTM carbon (a brominated carbon) 

was tested at Great River Energy’s Stanton Station Units 1 and 10 (8). Unit 10 is small (60 MW) 

boiler burning a North Dakota lignite with a SDA–FF combination, and Unit 1 is a larger boiler 

(150 MW) burning a PRB coal and operating an ESP. For Unit 1, the target of 60% mercury 

removal was achieved (ranged from 45% to 80%) at an average injection rate of only 

0.7 lb/MMacf. Tests are just getting under way on Unit 1. 

 In addition to using halogenated carbon, additives can be used with ACI to improve 

mercury removal for low-rank fuels. The EERC recently completed longer-term testing at 

Antelope Valley Station (AVS) using a combination of SEA with ACI (9). AVS fires North 

Dakota lignite and has a SDA–FF. Month long test results have shown that with only 0.81 

lb/MMacf ACI and 0.033 lb/MMacf of SEA, >90% mercury removal was achieved. This is 

compared to a near-zero baseline capture and 43% capture with ACI only. 
20 

 There has also been research ongoing to utilize other sorbent materials or substrates that 

are not carbon-based such as amended silicates. However, these materials have yet to be 

demonstrated at the full-scale level.

Economics of ACI 

 Based on an economic study done by Hoffman and Ratafia-Brown for DOE (10), it was 

estimated that the capital cost for ACI equipment for a 500-MW plant would be 

US$3–US$4/KW. For smaller systems, the cost can be as high as US$8/KW. Typically capital 

costs for an ACI system include the following: 

• Equipment transportation costs 

• Equipment installation costs including concrete pads and injection ports 

• Activated carbon storage silo 

• A feeder skid that includes blowers, variable screw feeders, and control system 

• Injection lances including piping and distribution manifolds 

 The following are variable operating and maintenance (O&M) costs associated with ACI: 

• Sorbent 

• Activated carbon disposal 

• Power 

• Operating labor 

• ACI equipment maintenance 

• Water (for spraying additives if used) 

• Cost of money (inflation and interest) 

 In addition to these items another potential cost would be the loss of revenue from selling 

fly ash and the resultant increased disposal costs. An alternative to lost ash revenue is installation 

of a FF. Costs for this option include capital improvements, pressure drop (increased power 

requirements), general maintenance of the baghouse, and bag replacement. Table 5 presents the 

total O&M cost for each plant in Canada based on the carbon usage for each plant (CCME). The 

cost of the sorbent is 90%–95% of the total O&M cost. 

References 

1. Feeley, T.J.; Brickett, L.A.; O’Palko, B.A.; Murphy, J.T.; Jones, A.P. An Update on the U.S. 

Department of Energy’s Phase II Mercury Control Technology Field Testing Program. In 
21 

Table 5. Additional O&M Costs for Canadian Power Plants as a Result of 

 Adding ACI (11) 

Power Station 

Net Capacity, 

MW Units 

Total O&M1 

For All Units, million $/yr (US) 

Alberta 

 Battle River 675 3 8.95–12.41 

 Sheerness 766 2 6.44–8.00 

 Genesee 1182 3 6.46–12.61

 Keephills 766 2 4.44–8.66 

 Sundance 2020 6 11.50–22.40 

Manitoba 

 Brandon 95 1 0.30–0.59 

New Brunswick 

 Belldune 450 1 02 

Nova Scotia 

 Lingan 600 4 1.32–4.92 

 Point Aconi 165 1 03 

 Point Tupper 150 1 0.60–1.16 

 Trenton 310 2 1.23–2.37 

Saskatchewan 

 Boundary Dam 814 6 5.11–19.86 

 Poplar River 562 2 3.38–13.08 

 Shand 279 1 1.71–6.60 1 O&M costs are based on a report to DOE (11). 2 Belldune is already achieving 70% mercury control (w-FGD). 3 Point Aconi is already achieving 60%–90% mercury control (CFB). 

2. Proceedings of the Air Quality V: Mercury, Trace Elements, SO3, and Particulate Matter 

Conference, Arlington, VA, Sept 19–21, 2005. 

3. Clean Air Compliance. North American Emissions Regulation and Markets. Argues Media

2005, 17 (01). 

4. Proposed Rules. Fed. Regist. Proposed Rules, 2004, 69 (230) 

www.epa.gov/mercury/control_emissions/noda.htm. 

5. Holmes, M.J.; Pavlish, J.H.; Benson, S.A.; Zhuang, Y. Developing Mercury Control Options 

for Utilities Firing Western Fuels. In Proceedings of the 19th Western Fuels Symposium; 

Billings, MT, Oct 2004. 
22 

6. Dombrowski, K.; Richardson, C.; Chapman, D.; Chang, R.; Monroe, L.; Berry, M.; 

Glessman, S.; Campbell, T.; McBee, K. Full-Scale Evaluation of Activated Carbon 

Injection. In Proceedings of the Air Quality V: Mercury, Trace Elements, SO3, and 

Particulate Matter Conference; Arlington, VA, Sept 19–21, 2005. 

7. Sjostrom, S.; Starns, T.; Wilson, C.; Amrhein, J.; Durham, M.; Bustard, J.; O’Palko, A.; 

Chang, R. Full-Scale Evaluations of Mercury Control for Units Firing Powder Basin Coals. 

In Proceedings of the Air Quality V: Mercury, Trace Elements, SO3, and Particulate Matter 

Conference; Arlington, VA, Sept 19–21, 2005. 

8. Nelson, S.; Landreth, R.; Liu, X.; Tang, Z.; Miller, J.; Weaver, D.; McMurray, R.; Potter, S.; 

Corey, Q.; McCoy, M.; Rogers, W.; Slye, R.; Ley, T.; Brickett, L.; Chang, R. Power-Plant 

Mercury Control Results with Brominated PAC and ESPs. In Proceedings of the Air Quality 

V: Mercury, Trace Elements, SO3, and Particulate Matter Conference; Arlington, VA, Sept 

19–21, 2005. 

9. Dombrowski, K.; Richardson, C.; Frenzel, D.; Ley, T.; Ebner, T.; Chang, R.; Strohfus, M.; 

Smokey, S.; Brickett, L. Full-Scale Activated Carbon Injection for Mercury Control in Flue 

Gas Derived from North Dakota Lignite and PRB Coal. In Proceedings of the Air Quality V: 

Mercury, Trace Elements, SO3, and Particulate Matter Conference; Arlington, VA, Sept 

19–21, 2005. 

10. Holmes, M.J.; Wocken, C.A.; Pavlish, J.H.; Hill Brandt, K.L.; Ericksen, B.; Brickett, L. 

Field Testing of Mercury Control for Lignite-Fired Systems with Activated Carbon and 

Sorbent Enhancement Additives: Field Test Results from Antelope Valley Station. In 

Proceedings of the Air Quality V: Mercury, Trace Elements, SO3, and Particulate Matter 

Conference; Arlington, VA, Sept 19–21, 2005. 

11. Hoffman, J.; Ratafia-Brown, J. Preliminary Cost Estimate of Activated Carbon Injection for 

Controlling Mercury Emissions from an Unscrubbed 500-MW Coal-Fired Power Plant; 

Science Applications International Corporation Final Report for U.S. Department of Energy 

National Energy Technology Laboratory, Nov 2003. 

12. Pavlish, J.H.; Laudal, D.L.; Holmes, M.J.; Hamre, L.L.; Musich, M.A.; Pavlish, B.M.; 

Weber, G.F.; Hajicek, D.R. Technical Review of Mercury Technology Options for Canadian 

Utilities – A Report to the Canadian Council of Ministers of the Environment; 2005-EERC03-07; March 2005. 
23 

MERCURY MEASUREMENT (QUARTER 2 REPORT) 

 With mercury regulations in place and full-scale, long-term demonstration of control 

technologies being conducted, measurement of mercury in combustion flue gas is of critical 

importance to demonstrate compliance and to allow evaluation of mercury control technologies. 

However, collecting a representative flue gas sample for mercury analysis presents many 

challenges owing to complex flue gas chemistry, high temperatures, mercury reactivity, and 

particulate loading. Given these challenges, many methods and instruments are available under 

varying degrees of development. 

 The most common approach for measuring mercury emissions from anthropogenic point 

sources consists of sampling train methods. Several common impinger-based methods include 

EPA Method 29, and the Ontario Hydro method (ASTM D6784-02). Each of these methods 

relies upon an isokinetic nozzle and filter to collect a flue gas sample, which is transported 

through a variety of liquid and solid sorbents to separate and preconcentrate gaseous mercury 

species. Quantification of the collected mercury species is then conducted using cold-vapor 

atomic absorption spectroscopy (CVAAS), cold-vapor atomic fluorescence spectroscopy 

(CVAFS), or energy-dispersive x-ray fluorescence (EDXRF). 

 A similar sample collection approach can also be applied to capture mercury species on a 

solid sampling medium through adsorption, amalgamation, diffusion, or ion exchange. These 

methods offer advantages in easier handling and greater stability; however, they are limited to 

time-averaging applications. Examples of these methods are the FAMS, QuickCEMs, and EON 

methods. 

 Real- or near-real-time data collection can only be obtained using continuous mercury 

monitors (CMMs). A large variety of CMMs are available utilizing a variety of flue gasconditioning approaches; however, all commercially available instruments measure elemental 

mercury and use either chemical or thermal treatment to convert mercury. As they are currently 

configured, CMMs possess several challenges to long-term, low-maintenance operation, the 

most significant of which include sample collection and flue gas conditioning. Mercury species 

reactivity and particulate loading make transporting a representative gas sample to the instrument 

a challenge and require heated sample lines and particulate removal techniques which prevent 

the buildup of a filter cake. Flue gas conditioning is an area where the greatest development is 

occurring. Wet-chemistry methods have typically been used to convert mercury to the elemental 

form that the analyzer can detect. These solutions are corrosive or caustic chemicals, and 

challenges associated with their use are considered the limiting factor in CMM reliability. Dry 

conversion units are now being marketed and are being used in field demonstrations. These 

systems focus on high-temperature catalysts and thermal reduction to convert oxidized mercury 

to the elemental form for analysis. It is anticipated that developments in this area will be the 

critical factor in ensuring real-time mercury measurements can be conducted reliably under 

steady-state operation.
24 

 The new regulations for mercury emissions from U.S. coal-fired boilers will require some 

form of continuous monitoring. EPA has announced that two measurement methods will be 

accepted: the sorbent trap methods as prescribed by 40 CFR, Part 75, Appendix K (Appendix K), 

and CMMs. Initially a number of utilities will opt for the sorbent trap methods; however, this 

could change as more robust CMMs become available. For both of these methods, EPA has 

established performance specifications (PS 12A), which relate to the setup, certification, and 

quality assurance/quality control (QA/QC) for each method. A summary of these specifications 

is provided; details can be found at www.epa.gov/mercuryrule. 

 Since May 2005, when the Mercury Information Clearinghouse second quarterly report 

was last updated, there have been a number of developments in mercury measurement, including 

the following: 

• Additional experience gained with 40 CFR, Part 75, Appendix K Specifications 

• Establishment of performance specifications and clarification of QA/QC requirements 

including relative accuracy test 

• Additional experience gained with next-generation CMMs 

• Possibility of an instrument-based reference method for mercury measurement 

Additional Experience with 40 CFR, Part 75, Appendix K Specifications 

To date, mercury emissions at over 85 stacks have been characterized using the twosection traps or the QuickCEM method (Dene). However, the QuickCEM as initially configured 

used only two sections, and Appendix K now requires the use of a third trap section designated 

for QA/QC purposes. The first two sections are still used to trap the gas-phase mercury and 

ensure there is no breakthrough. The third section is spiked with a known quantity of elemental 

mercury, and a correction factor based on the recovery is applied to the concentrations measured 

in the first two sections. Results presented at a recent Electric Power Research Institute (EPRI)-

sponsored mercury measurement workshop indicated there are problems with the consistency of 

the spiking and recovery of the third section. Spike recoveries as low as 30% have been 

observed. The existing spiking method needs to be refined or a new method developed in order 

to ensure reliable and consistent third sections that can be used for QA/QC. The addition of the 

third section has also increased the cost of the dry sorbent method. Traps with a spiked third 

section can cost from $590 to $710 per trap to purchase and analyze. This cost does not include 

the cost of equipment or labor. It is expected that during the next 1–2 years, costs will be reduced 

considerably as more cost-effective spiking and analytical methods are developed. 

QA/QC Requirements for Mercury Measurement RATAs 

 In the draft of PS 12A the paired reference method samples were required to be within 

10% of the relative standard deviation of the results. That requirement was changed in the final 

version. The paired samples are now required to meet the following relative difference (RD) 

criteria: 
25 

RD 

C C

(C C ) 100%

RD 10% for Hg concentration > 1 g / m

or

RD concentration 1 g / m

a b

a b

3

3

= −

+

×

≤

≤ ≤

μ

20% for Hg μ

Additional Experience Gained with Next-Generation Continuous Mercury Monitors 

In addition to the use of CMMs during large-scale mercury control demonstration projects, 

EPA (Segall) has been evaluating several commercially available CMMs at two tests sites (Sites 

1 and 2), which both burn eastern bituminous coals. Instruments that have been evaluated to date 

include the Tekran Model 3300, Thermo Electron Mercury Freedom System, Horiba/NIC DM6B, Forney/Genesis Model 6500, Durag HM-1400, and the Opsis HG200. In addition to these 

instruments, Appendix K sorbent traps were also tested. All of the instruments at some point 

have passed the initial certification requirements of PS-12A, but to date, only two instruments 

have passed at least one of the RATAs: the Thermo Electron (passed at the first site) and Tekran 

systems (passed at both sites). EPA is planning additional RATAs in 2006. The Thermo Electron 

instrument will be commercially available in late 2005 or early 2006. 

 Now that EPA has issued performance specification for mercury monitors, vendors have a 

much better idea of what will be required As a result, mercury measurement technology is 

moving forward rapidly, and reliable, rugged systems should be available well before the 

January 1, 2009, deadline. Mercury control demonstration projects are now using CMMs for 

long-term monitoring of mercury concentrations at stacks and other locations within the power 

plant with good success. These tests (3 to 6 months in duration) should provide additional data as 

to the overall reliability of CMMs. 

An Instrument-Based Reference Method for Mercury Measurement 

 A major concern for both certifying a CMM based on PS 12A and ongoing QA/QC 

requirement under 40 CFR, Part 75 is the requirement that all RATAs are to be conducted using 

the Ontario Hydro method. Obtaining nine valid paired sample trains is a challenge and will be 

very expensive for utilities. Therefore, EPA is trying to develop criteria for an instrument-based 

reference method. While a draft procedure may be available soon, there will be some major 

obstacles to overcome before an instrument-based reference method can be used. One of the 

main obstacles is the ability to dynamically spike both elemental (Hg0

) and oxidized mercury 

(Hg2+) to the tip of the sampling probe. Dynamic spiking requires the addition of a small amount 

of spike gas into the sample gas matrix. This is not required in the new regulations for the 

CMMs. All of the major CMM manufacturers are working on developing some type of mercury 

generation and delivery system. In order for the results from these systems to be accepted, they 

will need to be National Institute of Standards and Technology (NIST)-traceable. EPA has asked 

NIST to help provide traceability for gas standards. NIST is currently working on certification of 

Hg0

 gas cylinders and mercury gas generators, such as those provided by the PS Analytical and 

Tekran systems, for delivering Hg0

. They have determined that the expanded uncertainty for the 
26 

gas cylinders is approximately 6%, which is an order of magnitude higher than they usually get 

with other types of gas cylinders and not acceptable as a standard. A new equation for the 

mercury vapor pressure curves is also being proposed by NIST. Currently NIST, PS Analytical, 

and Tekran all use slightly different equations for Hg vapor pressure. NIST also plans to look at 

the long-term stability of the gas cylinders and mercury generators. 
27 

ADVANCED AND DEVELOPMENTAL MERCURY CONTROL TECHNOLOGIES 

(QUARTER 3 REPORT) 

 A variety of approaches for mercury control are under development, ranging from 

combustion modification to multipollutant technologies. Many of these unique technologies have 

passed the bench- and pilot-scale developmental phases and are now being tested at full scale. 

Many of these technologies were discussed in Quarter 3 and updated in Quarter 6 and include: 

• Pretreatment of coal to remove mercury. 

• Combustion modification and in situ generation of sorbents. 

• Non-carbon-based sorbent and amended silicates. 

• Stationary mercury traps positioned in the flue gas stream. 

• EnviroScrub Pahlman Process. 

• Combined oxidation of NOx and mercury. 

• Mercury control with the Advanced HybridTM Filter. 

 Since the amount of mercury in coal is very small (typically about 0.1 μg/g), the total 

amount of mercury input (and potential emissions) for a 500-MW plant in a year is only about 

300 lb. This suggests that there is potential for generating a minimum amount of waste material 

if the mercury can be effectively captured and concentrated. On the other hand, if the captured 

mercury is highly dispersed in waste material or by-product, the mercury must be proven to be in 

a stable form so that there is little possibility of reemission into the atmosphere. This will be a 

significant factor in the development of new technologies for long-term mercury control. 

Pretreatment of the Coal to Remove Mercury 

Removal of mercury from the fuel prior to combustion is a mercury control approach that 

has been considered for many years. Standard coal-washing methods for bituminous fuels to 

remove pyrites and other mineral matter result in the removal of some of the mercury; however, 

not to the extent that would be needed to meet future control requirements. Coal washing for ash 

reduction has proven to be effective primarily for bituminous fuels with large mineral grains. 

With subbituminous and lignite fuels, conventional coal washing is not effective because of the 

way the inorganic material is distributed within the coal. However, for subbituminous coals, 

deep cleaning or pretreatment of the coal, such as with the KFx K-Fuel process, has the potential 

to remove a significant fraction of the mercury. 

 A large-scale plant that can produce 750,000 tons per year of K-Fuel is nearing 

completion. The actual level of Hg reduction in the final fuel product as well as the fate of the 

removed mercury within the process will be demonstrated when the process becomes fully 

operational. PRB coals already account for about one-third of U.S. production and represent 

most of the growth in U.S. production in the last 10 years. Whether a significant portion of that 

production could eventually be upgraded as K-Fuel or similar products is primarily an economic 

one and highly dependent on tighter regulations. The current upward trend in world oil prices 

and focus on CO2 emission reduction would both appear to make K-Fuel more attractive in the 
28 

marketplace. The success of the first full-scale plant as well as the strength of the market will 

determine how fast new capacity is developed to meet demand. 

Another example of fuel-upgrading is the Great River Energy project, funded by DOE, 

which focuses on drying of high-moisture North Dakota lignite. The process does not claim to 

remove mercury from the lignite but upgrades the fuel with waste heat, resulting in overall plant 

efficiency improvement, with some subsequent reduction in mercury emissions. However, even 

with mild thermal processing of a raw fuel, there is potential for removing some of the mercury 

along with the moisture by increasing the drying temperature. 

In the recent Phase III RFP issues by DOE, one of the topics was new coal-cleaning 

technologies that would enhance mercury removal for lower-rank fuels. 

Combustion Modification and in Situ Generation of Sorbents 

An attractive approach to mercury control is to enhance the capture of mercury by 

modification of the combustion process to produce fly ash or unburned carbon that results in 

better mercury retention. The thought is that either increased carbon in the ash or generation of 

carbon in the ash with the appropriate characteristics will enhance mercury capture. Since lowNOx burner (LNB) technology is already known to produce more carbon in the ash, a logical 

extension of LNB approaches is to specifically modify the process for enhanced mercury control, 

such as is being investigated in a DOE-funded project by General Electric Energy and 

Environmental Research Corporation (GE EER) and Lehigh University. Another interesting 

approach is extracting a portion of the coal from the combustion zone and then quenching it prior 

to complete combustion to produce a material with good mercury sorption characteristics. This 

approach is know as the Thief process and is being developed at DOE NETL. Another somewhat 

similar approach is detailed in two EPRI patents that describe a method for in situ activation of 

carbon-based sorbents by injecting carbonaceous material at the appropriate location in a boiler. 

The largest single advantage for all three control technologies is that mercury capture 

could potentially be achieved with the coal. The GE EER process is the furthest along and is 

being tested at full scale. Of the three processes, this is also the simplest and would appear to be 

most likely implemented in the near future. One of the main concerns is that the process depends 

on incomplete combustion and the presence of significant unburned carbon in the ash. This 

makes fly ash utilization and disposal more challenging. 

The Thief process appears to offer more flexibility in achieving a much higher-capacity 

carbon but with additional complexity. Since the Thief process can include injection downstream 

of a primary particulate control device, it also offers an opportunity for separating the fly ash 

from the spent carbon. However, similar techniques can be implemented with many sorbent 

injection technologies. 

The EPRI process offers flexibility with the raw feed materials which may offer an 

opportunity to generate a very highly reactive, high-capacity sorbent. Since the generated 

sorbent material does not have to be collected and reinjected, the process may offer an 

opportunity to generate a very fine particle-size material. If so, in-flight capture would be 
29 

enhanced, making it an attractive application for ESP-controlled units. This process, however, 

has not been substantially tested, so near-term development is unlikely. 

Non-Carbon-Based Sorbent, Amended SilicatesTM 

ADA Technologies, Inc., has been developing a non-carbon-based mercury sorbent for 

several years. The Amended Silicates material will be tested in 2006 under the DOE-funded 

large-scale mercury demonstration program. Amended Silicates, LLC (a joint venture of ADA 

Technologies, Inc., and CH2M Hill), Littleton, Colorado, will test the material at Cinergy’s 175-

MW Miami Fort Unit 6 that burns bituminous coal. The research team also includes the EERC, 

Western Kentucky University, and Boral Materials Technologies. Current plans are for this 

testing to begin in February–March 2006. 

A sorbent that is non-carbon-based is highly attractive because of the potential for ash 

utilization without concern over additional carbon in the ash. Based on material properties and 

test results to date, no impact of the material on fly ash utilization is expected. 

 Critical developmental questions concern the level of control that can be demonstrated 

compared to existing and new activated carbons and the stability of the mercury in the ash. The 

ability to manufacture large amounts of the material at a reasonable cost also needs to be 

demonstrated. 

 The concept has moved beyond the bench-scale level and has been tested at the pilot level 

at a coal-fired power station. The current DOE-funded project will take the evaluation to the fullscale demonstration level. 

Stationary Mercury Traps Positioned in the Flue Gas Stream 

MerCAPTM 

The general MerCAP (Mercury Control via Adsorption Process) concept is to place fixed 

structures into a flue gas stream to adsorb mercury and then periodically regenerate them and 

recover the captured mercury. While a variety of regenerable sorbent materials could be used, 

most of the development work has focused on the use of gold-coated substrates in the form of 

parallel plates spaced about 0.5 to 1 in. apart. Previous work has shown that the level of control 

is impaired in an unscrubbed flue gas environment. Subsequently, current development efforts 

seek to achieve high levels of mercury removal in scrubbed flue gases, either downstream from a 

spray dryer scrubber or a wet scrubber. 

DOE NETL is currently funding a demonstration of MerCAP, conducted by URS Group. 

Testing has already been completed at Great River Energy’s Stanton Station, which burns North 

Dakota lignite, where MerCAP sorbent structures treated 6 MWe equivalence of flue gas when 

retrofitted into a single compartment in the outlet plenum of the Unit 10 baghouse. Additional 

testing is planned this year at Southern Company Services’ Plant Yates, which burns eastern 

bituminous coal. 
30 

The MerCAP process by itself has the potential to achieve >90% mercury removal when 

installed downstream of a scrubber. However, any upstream removal of oxidized mercury by the 

scrubber makes the total mercury removal of >90% even more likely. With regeneration, the 

mercury can be isolated for disposal, and since the mercury can be concentrated, permanent 

sequestering of the captured mercury is possible with a minimum volume of material. 

Since the concept depends on the amalgamation of mercury with gold, a key concern is the 

absorption ability of the gold as well as the regeneration ability and lifespan of the material. A 

very critical developmental question is how sensitive the material is to small concentrations of 

HCl or other gases that affect the absorption of mercury. In longer-term testing up to 5000 hr, 

actual mercury removal levels have only been in the range of 30%–40%. However, at the recent 

AQV Conference, URS reported that new regeneration technologies are being employed that 

enhance overall removal. 

W.L. Gore & Associates, Inc.,-Promoted Felt Filter Bag Inserts 

W.L. Gore & Associates, Inc., has developed an innovative technology for control of 

mercury emissions in flue gas streams. The configuration involves a mercury control filter 

placed inside the existing particulate control filter bag. This concept is similar to the MerCAP 

technology in that both attempt to achieve mercury capture by placing an adsorbent material in a 

convenient location within the system and then periodically (e.g., every 6 months) removing the 

components for regeneration and/or mercury concentration. 

The Gore mercury filter system has been tested at the small pilot-scale level both at EPA 

facilities and at the EERC. Operationally, the mercury filter elements did not appear to impair 

the pulse cleaning of the bags. Results showed that, initially, nearly 100% mercury removal 

could be achieved. However, for the materials tested, early breakthrough occurred under some 

conditions. The process appears to have potential, but currently there are no known testing 

programs outside of Gore to further develop this technology. 

EnviroScrub Pahlman Process 

A multipollutant control technology that is truly unique is being developed by EnviroScrub 

Technologies Corporation. In 2000, EnviroScrub acquired the dry PahlmanTM scrubbing 

technology, which can simultaneously remove SOx, NOx , and Hg. The Pahlman process uses a 

sorbent composed of oxides of manganese. These specialized sorbents have been generically 

named PahlmaniteTM sorbent in honor of the late Dr. John E. (Jack) Pahlman who led the early 

research and development work on the process. 

As presented, the technology is placed downstream of a particulate control device so that 

the captured mercury will not be mixed with the fly ash. This facilitates fly ash disposal as well 

as fly ash utilization as a by-product. 

The concept has moved beyond the bench-scale level and has been tested with a 

1000-acfm trailer-mounted slipstream device at a number of coal-fired power stations. However, 

only the collection step has been demonstrated. The fairly complex regeneration and recycling 
31 

steps have not been tested. Much longer-term and larger-scale testing needs to be completed to 

address all aspects of the process, but little additional development work has been done within 

the last year. 

Combined Oxidation of NOx and Mercury 

Two processes that oxidize mercury along with NOx for capture in an ammonia-based wet 

scrubber are unique. Both the BOC LoTOxTM and ECOTM/Powerspan are NOx control 

approaches whereby the NOx is oxidized to a soluble form to allow capture in a wet scrubber. 

Even though the oxidation approaches for the two processes are different, both of these 

processes claim that elemental mercury is also oxidized to HgO and subsequently captured in the 

wet scrubber along with SO2 and NOx. Both of the processes are coupled with an ammoniabased wet scrubber. 

LoTOxTM 

The BOC LoTOx system is based on the patented Low-Temperature Oxidation (LTO) 

Process for Removal of NOx Emissions, exclusively licensed to BOC Gases by Cannon 

Technology. Marsulex Inc. and the BOC Group have signed a joint marketing agreement that 

will enable each company to offer electric utilities an integrated multipollutant control solution 

that provides maximum compliance for emissions of sulfur dioxide, sulfur trioxide, nitrous 

oxides, mercury, and other heavy metals in conjunction with ammonia-based wet scrubbing. The 

LoTOx system is a NOx removal system that injects ozone into the flue gas stream to oxidize 

insoluble NOx to soluble oxidized compounds. The mercury removal is achieved by oxidizing 

elemental mercury with ozone to produce soluble HgO, which is captured in a downstream wet 

scrubber. The current status of the LoTOx process for mercury control is unknown. 

ECO/Powerspan 

Powerspan Corporation is the primary researcher and proprietary owner of the ECO 

process. However, Powerspan has entered into an alliance with Wheelabrator Air Pollution 

Control, Inc., to commercialize the system. Powerspan and First Energy jointly funded the latest 

pilot plant. In addition, DOE awarded a grant to Powerspan to optimize the mercury removal 

capability of the technology on a 50-MW demonstration facility at the R.E. Burger Plant. 

In the ECO process, flue gas exiting the ESP or FF is routed to the ECO reactor where it is 

exposed to a high-voltage discharge, which generates high-energy electrons. These high-energy 

electrons initiate chemical reactions that lead to the formation of oxygen and hydroxyl radicals. 

These radicals then oxidize the pollutants in the flue gas, leading to the formation of particulate 

matter and aerosol mist. These components are removed downstream in an ammonium salt wet 

scrubber and wet ESP forming the ammonium sulfate and ammonium nitrate by-products. 

Approximately 90% of the NO in the flue gas is oxidized to NO2 and is removed in the scrubber 

(the other 10% remains unoxidized). Less than 10% of the SO2 in the gas is oxidized to form 

SO3, which eventually forms sulfuric acid (H2SO4). Elemental mercury vapor is oxidized to form 

mercuric oxide (HgO), which is removed by the wet scrubber/wet ESP. 
32 

 Extensive mercury removal results have been reported in the last year from the pilot unit 

tests at the Burger Plant. Results showed that over 90% mercury removal was achieved, but most 

of the inlet mercury was already oxidized. Additional testing in which supplemental elemental 

mercury was injected upstream showed that up to 75% of the elemental mercury was converted 

to oxidized mercury across the reactor, and the total mercury removal for the system was still 

over 80%. Testing to evaluate removal of the collected mercury from the scrubber liquor showed 

that well over 90% of the mercury was removed so that in many cased the mercury level in the 

scrubber liquid was below detection limits. 

 FirstEnergy recently announced plans to install an ECO system on the 215-MW Unit 4 

boiler at its Bay Shore Plant in Ohio. 

Mercury Control with the Advanced HybridTM Filter 

 Since 1995, DOE has supported development of a new concept in particulate control, 

called the advanced hybrid particulate collector marketed as the Advanced Hybrid filter. The 

Advanced Hybrid filter combines the best features of ESPs and baghouses to provide ultrahigh 

collection efficiency, overcoming the problem of excessive fine-particle emissions with 

conventional ESPs. Additionally, it solves the problem of reentrainment and re-collection of dust 

in conventional baghouses. The Advanced Hybrid filter also appears to have unique advantages 

for mercury control over baghouses or ESPs as an excellent gas–solid contactor. Since most of 

the sorbent material will collect on the perforated plates, there will be minimal effect on the 

pressure drop across the filter bags. In addition, better gas–solid contact is achieved than in 

conventional ESPs because the distance that gas must cross streamlines to reach sorbent particles 

is much smaller than in ESPs. Mercury control with commercially available sorbents was 

demonstrated with a 2.5-MW Advanced Hybrid filter at the Big Stone Power Plant, which burns 

subbituminous coal from several different PRB mines. 

 Over 90% mercury control was demonstrated at low carbon addition rates upstream of the 

Advanced Hybrid filter with commercially available NORIT FGD activated carbon. However, 

the level of control was dependent on other flue gas components. One of the very interesting 

findings was the discovery that when the plant cofired a small amount of tire-derived fuel, the 

level of mercury captured in the fly ash, the fraction of oxidized mercury in the inlet flue gas, 

and the level of total mercury removal with activated carbon all were significantly increased, 

likely due to the increased chlorine content from tire-derived fuel. Another significant result was 

that the injection of activated carbon for mercury control had no effect on bag-cleaning interval 

or pressure drop. The perforated plate geometry of the Advanced Hybrid filter allows sufficient 

gas–solid contact to achieve over 90% mercury removal at low carbon addition rates, even 

though most of the carbon is collected on the perforated plates. 

 The concept for mercury control has moved beyond the bench scale and has been tested at 

the 2.5-MW pilot level at a coal-fired power station. However, there are currently no plans for a 

full-scale demonstration to evaluate mercury control effectiveness with the Advanced Hybrid

filter. 
33 

RERELEASE OF MERCURY FROM COAL COMBUSTION BY-PRODUCTS 

(QUARTER 4 REPORT) 

 At the time the CEA Quarter 4 report was written, only a limited amount of empirical data 

were available on mercury stability in coal combustion by-products (CCBs). Early work on 

rerelease of mercury from CCBs focused on developing and adapting methods to determine the 

potential for mercury to be rereleased from CCBs. Since that time, additional data have become 

available including results of field testing from mercury in ground and surface water at CCB 

disposal sites and vapor-phase mercury measurements at disposal and utilization sites. 

 In August 2005, DOE NETL selected Frontier Geosciences (Seattle, Washington) to 

conduct research on by-products generated from DOE’s mercury control program. As the 

majority of mercury control technologies result in additional concentrations of mercury being 

deposited in the fly ash or FGD material, Frontier will analyze multiple by-product samples for 

mercury and other elements from 31 different field sites. The tests will include volatilization, 

leaching (both abiotic and biotic), total element concentrations, and limited halide analyses (1). 

It is anticipated that some of the materials to be evaluated under the new DOE NETL program 

will include those with combinations of activated carbon and mercury capture-enhancing agents. 

Additional work is also expected on FGD materials under this program. 

 The most significant concern associated with CCB management and mercury emission 

controls continues to be the use of ACI to achieve mercury capture in the particulate control 

device. The result of ACI is an elevated carbon and mercury content in fly ash which has 

implications on ash reuse and raises concerns related to the stability of mercury in subsequent 

uses of the fly ash. The major utilization application for coal combustion fly ash is concrete and 

concrete products. The impact of ACI on ash suitability for the concrete industry has been 

apparent and reported by Starns (2) for an ACI demonstration at We Energies’ Pleasant Prairie 

Power Plant. Additional questions have been raised more recently about how additives, added to 

ACI systems to improve mercury capture, will impact not only fly ash, but other CCBs as well. 

While these additives are designed to enhance the removal of mercury from emissions, the fate 

of these chemical additives remains unclear and will also be investigated as mercury emission 

control testing continues. 

 The other CCB being evaluated relative to mercury capture and rerelease is FGD materials. 

FGD effluents had only been evaluated for mercury rerelease on a very cursory level at the time 

of the original report submission. Since that time, additional work has been done to determine 

total concentrations of mercury in various FGD materials as well as on the rerelease of mercury 

from FGD materials under different environmental conditions. 

Stability of Mercury on CCBs 

 Total mercury concentrations for CCBs are of interest because these data are valuable in 

developing mercury balances across emission control systems. Additional data have been 

reported by several groups primarily on those CCBs most directly impacted by potential mercury 

emission controls. Table 6 provides a summary of data on fly ash and FGD materials collected 
34 

Table 6. Total Mercury in CCBs and Mercury-Leaching Results Reported by Various Groups 

Information Source CCB Type 

Number of 

Samples in 

Sample Set 

Range of Total Hg 

(μg/g) Reported Leaching Method 

Number of 

Samples in 

Sample Set 

Range of Mercury Leachate 

Concentrations Hg, μg/L 

EERC (3) Fly ash without Hg 

control 

40 <0.01–2.03 Batch 

DI H2O 

72 <0.01–0.32 

EERC (3) Fly ash with Hg control 28 0.15–120 Batch 

DI H2O 

43 <0.01–0.07 

EERC (3) FGD material without Hg 

control 

10 <0.01–0.22 Batch 

DI H2O 

18 <0.01–0.40 

EERC (3) FGD with Hg control 1 0.33 

Schroeder and 

 Kairies (4) 

FGD gypsum 2 0.140–0.142 

Schroeder and 

 Kairies (4) 

FGD sludge – top layer 

(from nonoxidized wet 

scrubber) 

2 2.90–13.0 

Schroeder and 

 Kairies (4) 

FGD sludge – bottom 

layer (from nonoxidized 

wet scrubber) 

2 0.072–0.70 

Kim and Schroeder 

 (5) 

Fly ash without Hg 

control 

3 0.074–1.67 Column with 

H2O/ 

HAc/ 

Na2CO3/ 

SP/ 

H2SO4

3 

12.2–47.8 ng/g 

44.7–1614.8 

6.69–517.0 

0.39–9.34 

12.2–68.3 

Kim and Schroeder 

 (5) 

Fly ash with Hg control 6 0.348–92.1 Column with 

H2O/ 

HAc/ 

Na2CO3/ 

SP/ 

H2SO4

6 

2.74–845.8 ng/g 

35.5–410.1 

8.04–1263.1 

2.71–464.8 

4.15–147.7 

Withum (6) Fly ash 17 0.06–1.49 Batch leaching at 

pH 2.8/ 

pH 4.9/ 

DI H2O 

17 

All <1 

All < 1 

All <1 

Withum (6) FGD sludge (not fixated) 5 0.21–0.65 Batch leaching at 

pH 2.8/ 

pH 4.9/ 

DI H2O 

5 

<1–10.9 

<1–5.2 

All <1 

Withum (6) FGD sludge (fixated) 9 0.26–0.90 Batch leaching at 

pH 2.8/ 

pH 4.9/ 

DI H2O 

9 

<1–6.6 

<1–2.5 

All <1 

Withum (6) FGD gypsum 3 0.33–0.52 Batch leaching at 

pH 2.8/ 

pH 4.9/ 

DI H2O 

3 

All <1 

All <1 

All <1 

Withum (6) Bottom ash 2 0.01–0.04 Batch leaching at 

pH 2.8/ 

pH 4.9/ 

DI H2O 

2 

All <1 

All <1 

All <1 

Hower et al. (7) Fly ash 85 0.000–0.894 

Hower et al. (7) Bottom ash and boiler 

slag 

27 0.000–0.086 

Hower et al. (7) FGD (predominantly 

sulfate) 

7 (Av value) 0.176 

Hower et al. (7) FGD (predominantly 

sulfite) 

3 (Av value) 0.463 

Gustin (8) Fly ash without mercury 

control 

 Batch leaching 

SPLP 

23 0–8 ng/L 

Gustin (8) Fly ash with activated 

carbon 

 Batch leaching 

SPLP 

9 0–2 ng/L 

Gustin (8) FGD Batch leaching 

SPLP 

8 0–4 ng/L 

Starns (9) Fly ash without mercury 

control (baseline) 

2 291–734 ng/g Batch leaching 2 <0.0002 mg/L 

Starns (9) Fly ash with activated 

carbon 

2 1250–1520 ng/g Batch leaching 2 <0.0002 mg/L 
35 

without and with mercury emission controls present. These data are presented as ranges reported 

by the referenced researchers and may include data reported previously. 

 Hower et al. (10) also investigated the mercury concentrations of fly ash collected in 

various hoppers of an ESP at one power plant. He concluded that mercury capture is fairly 

uniform through an ESP system. 

Leaching1

 Table 6 also summarizes recent leaching data reported in several forums since October 

2005. EPA has performed leaching tests on a variety of CCB samples including fly ash samples 

with activated carbon, fly ash from systems with SCR on and off, and FGD materials (11), but no 

data were reported for inclusion in this update. The available leaching data indicate strong 

agreement among researchers (3–6, 8–9) that the mobility of mercury from direct leaching is 

very limited. In fact, the researchers (3, 5) have concluded that: 

• The leachate concentrations of mercury do not correlate to total mercury concentrations 

for fly ash samples. 

• Mercury in CCBs has extremely low mobility based on direct leaching. 

 Researchers (3, 5, 9, 12, 13) also all have reported that a range of leaching methods and 

leachate solutions provide similar results indicating extremely low concentrations of mercury in 

leachates. They and Schroeder (3, 5, 11) all have indicated that leachates from CCBs have 

mercury concentrations below the Drinking Water maximum contaminant level (MCL) of 

0.002 μg/mL. Thornloe (11) also stated that test values for mercury leachates indicate that 

engineering controls for CCB disposal are protective when compared both with MCL and the 

recommended ambient water quality criteria. Other data reported (3, 8) on leaching of fly ash 

samples without and with mercury control (activated carbon) indicated that the leachate 

concentrations of mercury are lower from fly ash with activated carbon present than fly ash that 

was generated without mercury controls, even though the total mercury content can be 

significantly higher for samples with activated carbon. 

Vapor Release2

 Evaluations of potential for vapor-phase rereleases both at elevated and ambient temperatures 

have been ongoing by several groups. 

 

1

 The authors of the various documents have reported data in several different formats. The following concentrations 

are equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per 

trillion) = pg/g, ng/L. The EERC has used ppm, ppb, and ppt to express concentrations associated with solid 

materials and vapor-phase releases. μg/L and ng/L have been used for concentrations in liquids such as leachate 

concentrations. 

2

 The authors of the various documents have reported data in several formats. The following concentrations are 

equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per 

trillion) = pg/g, ng/L. 
36 

Elevated Temperature Vapor-Phase Rerelease 

 Withum (6) performed volatilization tests on fly ash, FGD materials, spray dryer solids, 

and products that incorporated CCBs (aggregate, cement, and wallboard) at 100° and 140°F with 

a continuous Hg-free nitrogen purge. The experiment duration was 6 months and indicated no 

detectable mercury loss from most samples; however, Withum did indicate that there were 

sampling and storage difficulties with the samples used in the effort. Hower et al. (10) used 

thermal gravimetric analysis (TGA) to evaluate the potential for mercury releases at elevated 

temperatures and concluded that mercury was not released until 300°C. Starns evaluated baseline 

fly ash samples (without mercury control) and comparable fly ash samples with PAC from two 

different demonstrations of mercury emission controls for thermal stability and reported that for 

both demonstrations, the thermal stability of mercury increased when PAC was present in the 

sample, as evidenced by increased first mercury desorption peaks (240°C for baseline compared 

to 315°C for fly ash–PAC for one site and 358°C for baseline compared to 419°C for the fly ash–

PAC from a second site). Pflughoeft-Hassett (3) generated mercury thermal desorption curves 

for 61 CCBs, including 36 samples without mercury control and 25 samples with mercury 

control. The samples were primarily fly ash but also included various types of FGD materials. 

Most samples generated either one or two mercury peaks with a range of 0–4 peaks. The 

temperature of the mercury peaks ranged from 256° to 750°C, with an average of 429°C. Some 

samples continued to show increasing mercury release at 750°C, so the peak temperature at 

which the mercury was released could not be determined. FGD materials tended to release 

mercury at a lower temperature than fly ash. Fly ash samples with activated carbon were more 

likely to indicate continued mercury release at 750°C than fly ash generated without any mercury 

controls present. 

Ambient-Temperature Vapor-Phase Rerelease 

 Gustin et al. (8) reported on ambient-temperature releases for air–CCB mercury exchange 

experiments performed under varied laboratory conditions (temperature, time, light, and dark). 

Gustin also investigated the impact of loss on ignition (LOI) and moisture on mercury release in 

laboratory experiments. She concluded that deposition (or sorption) was the predominant 

atmospheric flux (air–CCB mercury exchange) for fly ash from bituminous and subbituminous 

coal. Fly ash from lignite was found to emit mercury. Fly ash with activated carbon present 

sorbed mercury from the atmosphere at a higher rate than fly ash without activated carbon. Wet 

FGD material had a higher potential to release mercury to the atmosphere than dry FGD material 

or fly ash, and water content greatly influenced emission or release rate. 

 The ambient-temperature release of mercury was also investigated by Pflughoeft-Hassett 

(3) on 19 CCB samples. In long-term release measurements, six of the samples showed overall 

mercury release and 13 samples showed overall mercury sorption. Pflughoeft-Hassett also 

indicated that a wet FGD material included in these experiments released considerably more 

mercury than fly ash or dry FGD as long as the sample remained wet, but after the water 

evaporated from the sample the mercury release rate slowed. 
37 

Microbiologically Mediated Release 

 The EERC (3) continued its efforts to quantitate mercury rerelease from fly ash and FGD 

materials on exposure to microbiological activity. Improved methods were described and 

included measurement of the rerelease in the liquid phase as well as the vapor-phase for 

elemental and organomercury. Aerobic and anaerobic glucose-fed conditions were used in the 

experiments on fly ash and wet limestone FGD filter cake material. The fly ash samples 

evaluated were both from lignite-fired power plants with total mercury contents of 0.689 μg/g 

and 0.785 μg/g. The FGD material had a mercury content of 0.218 μg/g and a significant natural 

population of sulfate-reducing bacteria. The FGD material had an average vapor-phase release of 

0.13 pg/g/day under anaerobic conditions and 9.44 pg/g/day under aerobic conditions during a 

3-week time period when the samples were being pH-stabilized with buffer addition. This 

release was attributed to the naturally occurring sulfate-reducing bacteria in the FGD material. 

Following the preliminary pH adjustment phase, the highest vapor-phase release of both 

elemental and organomercury was from the FGD material under aerobic conditions, even though 

it had the lowest level of total mercury. Analytical difficulties were noted and interfered with the 

final analysis of vapor-phase mercury release from the FGD material. The fly ash samples 

released similar levels of vapor-phase mercury in these experiments ranging from 0.036 to 0.147 

pg/g/day elemental mercury and from 0.108 to 1.25 pg/g/day for organomercury. Organomercury 

was also measured in the liquid separated from these experiments. Again the FGD material had 

significantly greater concentrations of organomercury in solution compared to the fly ash 

samples with a release of ~1800 pg/g for anaerobic conditions and a release of ~400 pg/g for 

aerobic conditions. Fly ash releases were 70 pg/g and 170 pg/g for anaerobic conditions and 128 

pg/g and 195 pg/g for aerobic conditions. The EERC indicated that the data were variable and 

that work would continue on the experimental release method and the analytical methods to 

address interference from sulfur in the samples and the development of mold in the samples 

during the experiments. 

Field Studies of Mercury Releases 

Disposal Site Water Evaluations 

 Withum (6) evaluated groundwater collected at active fly ash and FGD disposal sites using 

existing monitoring wells. No mercury was detected in any monitoring well samples. Ladwig 

(14) also collected and evaluated a variety of water samples from a large number of CCB 

disposal sites (including ash ponds, ash landfills, and FGD disposal sites) across the United 

States. Samples collected and analyzed were from the following locations depending on the site: 

• Leachate wells 

• Lysimeters 

• Leachate collection systems 

• Drive point 

• Direct push 

• Pond/seep grab 

• Sluice lines 
38 

 Data were summarized by site type (see Figure 2), and Ladwig indicated that the mercury 

concentration range was low at 0.25 to 60 ng/L, with a median concentration of 3 ng/L. Methyl 

mercury was generally less that 1 ng/L, and dimethyl mercury was usually not detected. 

Field Vapor-Phase Releases 

 Xin et al. (16) presented results of field studies designed to determine mercury flux. A 

variety of disposal sites at facilities utilizing bituminous, subbituminous, and lignite were 

included in Xin’s work. Table 7 summarizes Xin’s findings. 

 A summary of similar work also performed by University of Nevada Reno (UNR) 

indicated that field data were consistent with laboratory data, with bituminous and 

subbituminous fly ash disposal sites sorbing mercury from the atmosphere, while lignite-derived 

fly ash exhibited emissions even though in the field that emission rate was low and comparable 

to surrounding soil (8). 

 The EERC collected mercury from ambient air at near-surface locations at one field site in 

conjunction with the UNR work (16) and quantitated the concentrations of elemental and 

organomercury. Elemental mercury concentration ranged from 0.541 ng/m3

 (the FGD + bottom 

ash and mill rejects) to 1.456 ng/m3 (above FGD + mill rejects). Samples collected above natural 

grassland upwind from the associated power plant had 0.640 ng/m3 of mercury. For 

organomercury, the sample collected above the natural grassland gave a reading of 0.017 ng/m3

. 

Samples collected above various disposal sites ranged from 0.006 ng/m3 (FGD + pyrite) to 

Figure 2. Field leachate – mercury speciation (15). 
39 

Table 7. Summary of Field Mercury Flux Data Presented by Xin et al. (16) 

Coal Type Used at 

Associated Power Plant 

Material Type Where Flux 

Measurements Were Taken 

Mercury Flux (+ indicates 

release, - indicates sorption), 

ng/m2

hr 

Bituminous– 

 Subbituminous Blend 

Vegetated top soil over fly ash -0.1 

Bituminous– 

 Subbituminous Blend 

Barren fly ash +0.9 

Bituminous– 

 Subbituminous Blend 

Background soil +0.5 

Lignite Vegetated top soil over fly ash +1.1 

Lignite Barren fly ash +1.1 

Lignite Unstabilized wet FGD material +0.8 

Lignite Wet FGD material + fly ash or pyrite +11.2 or +10.9 

0.354 ng/m3

 (FGD + fly ash); however, the value measured for the FGD + fly ash was 

significantly higher than other values (0.006–0.052), and the standard deviation was also high. 

Rerelease of Mercury from CCBs in Select Utilization Applications 

 Gustin et al. (8) used outdoor experiments to evaluate the potential for rerelease of 

mercury from CCBs. Her experiments were designed to simulate soil stabilization, compacted 

CCB pads, and agricultural soil amendment, and while work will continue, preliminary data 

indicated that the mercury flux from CCB-amended substrates was not significantly different 

from soils used. Golightly et al. (17) captured the volatile mercury species in air directly above 

curing concrete specimens. The specimens included OPC (ordinary portland cement) concrete, 

concrete with 33% fly ash added, concrete with 55% fly ash added, and concrete with 33% fly 

ash and 0.5% mercury-loaded PAC. Sampling was performed at 2 days, 28 days, and 56 days 

during dry curing at 40°C. Results are shown in Table 8. Golightly et al. (17) concluded that 

laboratory experiments suggested that curing fly ash concretes contribute little to global 

anthropogenic mercury emissions but that field work needs to be performed. 

 Another area of investigation of potential rerelease of mercury from CCBs has focused on 

FGD gypsum which is used in the production of wallboard. Since gypsum (natural or byproduct) needs to be calcined before use in the wallboard-manufacturing process, questions have 

been raised as to the potential for mercury to be released during the calcining or other phases of 

the process. Heebink et al. (18) performed laboratory investigations on an FGD gypsum designed 

to simulate two types of gypsum calcining (kettle and flash). Heebink reported a range of 

releases from <0.4%–28% of total mercury content present in the FGD gypsum samples 

evaluated, and Heebink concluded that there was potential for mercury to be released from FGD 

gypsum in the calcining process used in wallboard-manufacturing plants and that release 

appeared to be related to total mercury content of the gypsum being used. 
40 

Table 8. Mercury Emission from Dry-Curing Concretes 

 Mass Release Rate, ng/day/kg 

Curing Interval 

OPC 

Concrete 

FA33 

Concrete 

FA55 

Concrete 

HgPAC 

Concrete 

n 4 6 3 4 

First 2 Days 

 [40 ± 1 °C] 

0.07 ± 0.02 0.13 ± 0.07 0.08 ± 0.07 0.26 ± 0.04 

First 28 Days 

 [40 ± 1 °C] 

0.10 ± 0.03 0.26 ± 0.04 0.34 ± 0.09 0.43 ± 0.12 

n 2 0 1 2 

Additional 28 Days, 

 [23°C ≤ T ≤ 40°C] 

0.08 ± 0.05 – 0.10 0.11 ± 0.01 

Initial Mercury 

 Concentration in 

 Concrete, μg/kg 

4.1 9.2 12.6 22.4 

 Marshall et al. (19) reported on an evaluation of mercury releases from FGD gypsum at a 

variety of full-scale wallboard plants using FGD gypsum from several sources. The effort 

included an evaluation of mercury releases from gypsum drying, gypsum calcining, and 

wallboard drying. Using Ontario Hydro and solids analysis, Marshall reported that the mercury 

releases ranged from 2.3% to 55% of the total mercury content of the FGD gypsum for all 

wallboard processes evaluated and estimated that a wallboard plant could potentially emit 

approximately 71 lb of mercury per year. In laboratory experiments, Kairies et al. (20) 

investigated the distribution of mercury in FGD gypsum and found that FGD gypsum is 99% 

soluble using a continuous stirred reactor, but that the remaining 1% solid residue contained 

100% of the mercury present in the original FGD gypsum sample. Wallboard solubility was 

similar, with 2% residue remaining containing 100% of the mercury from the original wallboard. 

Experiments were also designed and performed to determine the partitioning of mercury when 

FGD gypsum settles. These experiments indicated that after settling, the majority of the mercury 

was present in the top layer, while the bottom layer had very low mercury content. The top layer 

was also enriched in iron, and Kairies et al. (20) concluded that an iron-containing phase is 

responsible for sorption of mercury. 

Summary 

 A large amount of work has been accomplished and reported related to the rerelease of 

mercury from CCBs since October 2004. The rerelease mechanism that has the most data 

available is that of direct leaching. Direct leaching evaluations have been performed primarily on 

fly ash, with limited activities on FGD materials. Several groups have reported similar results 

from leaching tests of fly ash generated both without and with mercury controls. The reports 

reviewed generally indicated that direct leaching of mercury from fly ash, even with elevated 

mercury concentrations, is not expected to require changes to current fly ash management 

options. 
41 

 The remaining mechanisms, vapor-phase rerelease and microbiologically mediated 

leaching and vapor-phase rerelease, have also been investigated during the past year, with 

additional information reported in the literature. However, the data available are still too limited 

for conclusions to be drawn. For the vapor-phase rerelease evaluations, results reported from 

studies performed by different investigators indicated similar ranges of rerelease or sorption 

from similar materials. To date, the microbiologically mediated rerelease work has been limited 

to work performed at the EERC under a DOE NETL and industry-funded project. It is also 

noteworthy that the field-generated data are consistent with the reported laboratory data even 

though only limited field investigations have been performed. 

 When the DOE NETL-funded project to conduct research on by-products generated from 

large-scale mercury emission control demonstrations is initiated, it is anticipated that a large 

number of CCB samples will be evaluated for mercury volatilization and leaching (both abiotic 

and biotic). The data from this study will help to fill the existing data gaps and contribute to the 

information available to aid the CCB industry in making decisions on management of CCBs that 

have been impacted by mercury emission controls. 

References 

1. American Coal Ash Association. ACAA Newsletter. www.acaausa.org/ACAA%20E%20Newsletter/Sep-2005_Newsletter.htm#DOE (accessed Oct 2005).

2. Starns, T.; Bustard, J.; Durham, M.; Lindsey, C.; Martin, C.; Schlager, R.; Donnelly, B.; 

Sjostrom, S.; Harrington, P.; Haythornthwaite, S.; Johnson, R.; Morris, E.; Chang, R.; 

Renninger, S. Full-Scale Test of Mercury Control with Sorbent Injection and an ESP at 

Wisconsin Electric’s Pleasant Prairie Power Plant. Presented at the Air & Waste 

Management Association Annual Meeting, Session AE1-C, 2002. 

3. Pflughoeft-Hassett, D.F. Mercury and Air Toxic Element Impacts of Coal Combustion ByProduct Disposal and Utilization. Presented at the U.S. Department of Energy National 

Energy Technology Laboratory Mercury Control Technology R&D Program Review, July 

2005. 

4. Schroeder, K.; Kairies, C. Distribution of Mercury in FGD Byproducts. Presented at the 

2005 World of Coal Ash (WOCA), Lexington, KY, April 2005. 

5. Kim, A.G.; Schroeder, K. Factors Controlling the Solubility of Mercury Adsorbed on Fly 

Ash. Presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005. 

6. Withum, J. Characterization of Coal Combustion By-Products for the Re-Evolution of 

Mercury into Ecosystems. Presented at the U.S. Department of Energy National Energy 

Technology Laboratory Mercury Control Technology R&D Program Review, July 2005. 
42 

7. Hower, J.C.; Robl, T.L.; Anderson, C.; Thomas, G.A.; Sakulpitakphon, T.; Mardon, S.M.; 

Clark, W.L. Characteristics of Coal Combustion Products (CCPs) from Kentucky Power 

Plants, with Emphasis on Mercury Content. Fuel 2005, 84, 1338–1350. 

8. Gustin, M.; Xin, M.; Ladwig, K.; Pflughoeft-Hassett, D.; Ericksen, J.; Swain, E. Coal 

Combustion By Products: Do We Need to Worry about Hg Releases. Presented at Air 

Quality V: International Conference on Mercury, Trace Elements, SO3, and Particulate 

Matter, Arlington, VA, Sept 2005. 

9. Starns, T.; Sjostrom, S.; Amrhein, J.; Sapp, C.; Wilson, C.; Zipp, E.; Senior, C. Evaluation 

of Fuel Samples and Process Byproducts form Full-Scale Mercury Control Evaluations 

Conducted on Coal-Fired Boilers Burning PRB Fuel. Presented at Air Quality V: 

International Conference on Mercury, Trace Elements, SO3, and Particulate Matter, 

Arlington, VA, Sept 2005. 

10. Hower, J.; Rubel, A.; Mardon, S.; Perrone, R. Thermal Stability of Mercury Captured by Fly 

Ash. Presented at the Western Fuels Symposium, Billings, MT, Oct 2004. 

11. Thorneloe, S. Atmospheric Protection Branch/NRMRL. Personal communication, 2005. 

12. Schroeder, K.; Cardone C.; Hesback, P.; Kairies, C., Kazonich, G.; Kim, A. NETL In-House 

Characterization of Mercury in Coal Combustion By-Products. Presented at the U.S. 

Department of Energy National Energy Technology Laboratory Mercury Control 

Technology R&D Program Review, July 2005. 

13. Lockert, C.A.; Zhou, Q.; Zhang, Y.; Nelson, S. Further Progress Toward Concrete-Friendly 

Mercury Sorbents. Presented at Air Quality V: International Conference on Mercury, Trace 

Elements, SO3, and Particulate Matter, Arlington, VA, Sept 2005. 

14. Ladwig, K. Speciation and Attenuation of Arsenic and Selenium, and Fate of Mercury in 

CCPs. Presented at the U.S. Department of Energy National Energy Technology Laboratory 

Mercury Control Technology R&D Program Review, July 2005. 

15. Ladwig, K. Mercury in Coal Combustion Products. EPRI, Palo Alto, CA: 2005. 1010061. 

16. Xin, M.; Gustin, M.S.; Ladwig, K. Mercury Release from Coal Combustion Products; 

Presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005. 

17. Golightly, D.W.; Sun, P.; Cheng, C.; Taerakul, P.; Walker, H.W.; Weavers, L.K.; Wolfe, 

W.E.; and Golden, D.M. Mercury Emissions from Concrete Containing Flu Ash and 

mercury-Loaded powdered Activated Carbon; presented at the 2005 World of Coal Ash 

(WOCA), Lexington, KY, April 2005. 

18. Heebink, L.V.; Hassett, D.J. Mercury Release from FGD. Presented at the 2003 

International Ash Utilization Symposium; Special Issue of Fuel 2005, 84 (11), 1372–1377. 
43 

19. Marshall, J., Blythe, G.M.; Richardson, M.; Rhudy, R. Fate of Mercury in Synthetic 

Gypsum Used for Wallboard Production, Task 1. Presented at Air Quality V: International 

Conference on Mercury, Trace Elements, SO3, and Particulate Matter, Arlington, VA, Sept 

2005. 

20. Kairies, C.L.; Schroeder, K.T.; Cardone, C.R. Distribution of Mercury in FGD Materials. 

Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO3, and 

Particulate Matter, Arlington, VA, Sept 2005. 
44 

MERCURY FUNDAMENTALS (QUARTER 5 REPORT) 

 A review of the fundamental chemical principles of sorbent control of mercury in coal 

combustion flue gas was recently presented in Quarter 5. This update will summarize some of 

the earlier discussion as well go into more depth in certain areas of sorbent science. 

Understanding these fundamentals is critically important in the ongoing efforts to improve 

mercury capture and lower emissions from combustion sources. For low-chlorine coals, much of 

the mercury in the flue gas is elemental (Hg0), and only a small amount is oxidized Hg(II), but 

finely powdered sorbent injection upstream of a particulate collection device has the potential to 

capture both elemental and oxidized mercury present in the flue gas. 

 There are several facts and ideas that have been developed in the last few years that are 

critical to understanding how the capture of mercury takes place on a carbon sorbent in a flue gas 

stream. Several unequivocal pieces of evidence demonstrated that the sorption at elevated 

temperatures occurs via an oxidation mechanism (chemisorption) rather than physisorption. The 

most important evidence is the results of the examination of spent sorbents using x-ray 

absorption fine structure (XAFS). These studies showed that only Hg (II) was present (1). 

Flue Gas Effects 

 Based on results from an extensive matrix of tests at the EERC using full and partial gas 

compositions (2), a preliminary chemisorption model was developed (3). The model showed 

both oxidation of elementary mercury on the carbon surface and binding of the oxidized mercury 

to a basic site on the carbon surface. The model was supported by x-ray photoelectron 

spectroscopy (XPS) data for a number of experiments where a sorbent was exposed to various 

synthetic flue gas compositions for varying lengths of time (4). These data demonstrated the 

competitive role of the acidic flue gas components and sulfuric acid formed by oxidation of SO2

at the basic binding sites on the carbon. An updated version of this chemisorption-competitive 

binding model is shown in Figure 3. NO2 is shown to effect the oxidation of SO2 to H2SO4 or 

HSO4- on the carbon surface, a reaction that also requires H2O. Note, however, that the details of 

the mercury oxidation reaction as well as the SO2 oxidation are not included nor are the 

interactions of SO3. Thus this illustration is an overview of the reactions on the carbon, with no 

mechanistic details. 

Carbon Structure Effects 

 Published information of the effect of carbon structure on the capacity or reactivity of 

sorbents is very scant. The effect of oxygen functional groups on the sorbent surface was 

investigated by Ghorishi et al. (5), but they found no correlation with mercury capture. 

Regarding the effect of carbon crystallinity, there is little except the recent report by Rostam 

Abadi et al. (6). The capture of mercury on the unburned carbon (UBC) of fly ashes was 

examined, with very careful attention to the particle size and structural organization of the UBC 

fractions from three different ashes (6). The UBC content decreased with decreasing particle size 

for all three ashes. There was no correlation between the mercury content and UBC content of 

different size fractions; however, mercury content of unburned carbons in each size fraction 
45 

Figure 3. Overview of mercury flue gas interactions on an activated carbon sorbent. 

increased with decreasing particle size for the three ashes. After a normalization with respect to 

surface area, the data showed a more pronounced dependence on size for the FA1 (baghouse 

ash). The implications are that the size of the FA1 UBC and the surface area both contributed to 

the capture, whereas for FA2 (ESP ash) UBC particles size had a larger effect on mercury 

capture than the surface area, and for FA3 baghouse UBC, the size had a larger effect than 

surface area. 

 Comparison of the x-ray diffraction (XRD) spectra of UBCs with activated carbon and 

with graphite, showed that the UBCs have a less disordered structure than activated carbon. Thus 

the higher temperature in the combustion system resulted in more extensive ordering and 

consequently lower surface areas than activated carbons and lower mercury capture potential. 

The FA3 UBC was the most ordered and exhibited the lowest mercury capture. The implications 

for mercury capture in coal-fired boilers are that decreasing the UBC size will result in more 

capture. Also a lower temperature history for the UBC would result in less ordered carbon 

structures that are favored for mercury capture. 

Acid Promotion Effects 

 In early work, an increase in sorption was observed when HCl was added to flue gas (7), 

but the reason for the success of this strategy was unknown. It is clear that HCl is not an 

oxidizing reagent, since it is already in the most reduced state. The possibility of a Deacon 

reaction of HCl with oxygen on the carbon sorbent could account for generation of an oxidant on 

the sorbent surface. In the test matrix conducted at the EERC (2), when relatively high HCl 

concentrations (50 ppm) typical of eastern bituminous coals were used, the capture of mercury at 
46 

the start was always very high (less than 5% of inlet concentration), but in very low HCl 

concentrations (1 ppm), such as those obtained when low-Cl coals are burned, an initial 

breakthrough was observed at only about 50%B60% of inlet (8), followed by an increase in 

capture efficiency to the 5%–10% level (Figure 4). The higher HCl concentration thus eliminated 

this induction period where poor capture is obtained (9). Since the increased sorption activity is 

seen from the very start of exposure to the flue gas, this increased activity is clearly a kinetic 

effect and therefore results from a promotional effect of the HCl on the carbon sites catalyzing 

the oxidation of mercury (9). 

 XPS studies of carbons exposed to synthetic flue gas showed that in either high-HCl or 

low-HCl conditions, the chlorine concentration on the carbon surface builds up at first, but then 

diminishes at breakthrough when the sulfuric acid displaces the bound chlorine (4, 10). These 

studies showed that the chlorine is present mainly in two forms, organochlorine and chloride ion. 

 An increase in capacity for carbons that were pretreated with dilute aqueous HCl was 

reported by Ghorishi et al. (5). The effect was observed in both nitrogen and synthetic flue gas. 

Experimentation at the EERC (9) showed that the main effect was the same as that observed for 

flue gas containing HCl, as discussed above. A more detailed chemical model of the carbon 

bonding site was introduced (11) to explain the bonding of the HCl, Hg(II), and the competition 

with the poisoning agent the sulfuric acid generated by oxidation of SO2 on the sorbent. 

The model, shown in Figure 5, uses the concept of zigzag carbene edge structures recently 

proposed by Radovic and Brockrath (12). The zigzag carbon flanked by the aromatic rings has 

an electron pair and is the basic binding site for which the HCl, H2SO4, and Hg(II) compete, as 

shown on the left side of the figure, forming a positive carbenium ion intermediate in each case. 

Figure 4. Breakthrough curves for high and low acid gas. 
47 

Figure 5. Mercury and acid gas-binding mechanism at carbon edge. 

Mercury Oxidation Mechanism 

 Several features of the oxidation site were inferred from the HCl promotion and bonding 

effects (9) that led to development of a more comprehensive model (Figure 6) of the chemical 

mechanism of mercury capture (9, 13, 14). This mechanism uses a single carbon site for 

oxidation and bonding but in two different forms and thus offers more chemical detail on the 

nature of the oxidation-bonding site and its interaction with flue gases and mercury. The model 

thus provides a detailed mechanism for the catalytic role of acids, such as HCl, in the oxidation 

step. The conversion of carbene to carbenium ion by HCl and other acids generates the oxidation 

site (Lewis acid). The mechanistic model shows Hg0

 oxidation by the carbenium cation to the 

organomercury intermediate and subsequent oxidation by NO2 to the bound Hg(II) species. At 

the breakthrough point, HgCl2 is continuously released as sulfuric acid drives the formation of 

the carbenium sulfate. Comparative testing of a large number of acid-promoted AC showed that 

they exhibit a specific acid catalysis, not a general acid catalysis. That is, those acids with 

polarizable counterions (HI>HBr>HCl) show faster initial rates compared with strong and weak 

oxyacids and fluoroacids (13). This finding is consistent with a mechanism where the halide ion 

proximate to the cation actually can assist in the oxidation mechanism by stabilizing the incipient 

mercurinium ion forming in the transition state. 

Halogenated Carbons 

 It has been known since 1934, when the first patent for mercury sorption was granted, that 

adding molecular halogens such as chlorine (Cl2), bromine (Br2), or iodine (I2) to carbons results 

in effective sorbents for Hg0

 capture in air (15). The first application used iodine as the halogen, 
48 

Figure 6. Oxidation mechanism – carbenium ion oxidant. 

but later applications used chlorine (16) and bromine (17) or a mixed halogen compound (18). 

Originally, the model for this type of sorbent was that the halogens on the carbon were 

responsible for reactions with the Hg0

, but a considerable amount of chemical evidence (19) 

showed that the halogens that are impregnated into carbon react with the carbon and are strongly 

bound to the carbon. So it is more likely that the halogens promote the reactivity of the carbon, 

as we have demonstrated for HCl, rather than react as such with the Hg0. 

 To provide greater insight into the mechanisms for mercury capture on a chlorine-treated 

sorbent, a comparison of the structures and mercury sorption activities of several carbon sorbents 

that had been subjected to various chlorine treatments was recently conducted (20). The NORIT 

FGD carbon was pretreated with gaseous HCl, aqueous HCl, and gaseous Cl2. All the pretreated 

sample showed high initial activity for capture, and thus the induction peak has been eliminated. 

Exceptionally high capacities were not observed since the ability to oxidize SO2 to sulfuric acid, 

the main position of the binding sites, is not impaired by the chlorination. 

 Several of the pretreated sorbents were exposed to flue gas containing elemental mercury 

for various lengths of time, and the samples were analyzed with XPS. The Cl spectra of the 

pretreated samples that had not been exposed to flue gas showed peaks corresponding to both 

organochlorine and inorganic chloride. No clearly resolved peaks for physisorbed or intercalated 

molecular chlorine were found, but some may have been present in the wings of the 

organochlorine peak at high energy. As a result of exposure to the flue gas for a short time 

(20 min), all the chlorine-treated samples lost chlorine, but mainly the inorganic chloride. This 

could have been lost as HCl via displacement by sulfuric acid as it began to accumulate, as 

predicted by the model. Heating the chlorinated sorbents in air or an inert gas did not evolve 

either HCl or Cl2, so the chlorine is strongly bound and must be exchanged or reacted off the 
49 

carbon by a strong acid. Further exposure to flue gas resulted in further loss of both 

organochlorine and inorganic chloride. Although these chlorine spectra indicate the structures of 

the chlorine but not the mercury, the results contribute to our understanding of the reactive sites 

and allow us to extend the model to the chlorinated sorbents with little modification (see 

Figure 5). 

 The mechanism depicted in Figure 7 shows chlorination of the carbon edge structure to 

form the organochlorine species, consisting of the dichloro intermediate in equilibrium with the 

chlorocarbenium chloride ion pair. The latter represents the active oxidation site for elemental 

mercury, and the result of the oxidation is the organomercury chloride. The breakthrough 

mechanism proceeds as with the unchlorinated carbon (Figure 6). 

Potential for More Effective Capture 

 Owing to the high reactivity of the halogenated carbons, full-scale testing of these sorbents 

is being conducted. Preliminary results show that indeed the halogenated carbon capture mercury 

more effectively and faster. Since improved capture is found in ESP systems for halogenated 

carbon injection, the capture is not mass transfer-limited even in these short contact time 

situations. 

Figure 7. Mercury oxidation mechanism for chlorinated carbon. 
50 

 A better understanding of the interactions and effects of flue gas constituents and 

conditions has resulted in an improved mechanistic model and the development of more 

improved sorbents for mercury capture and control. We can actually derive and compare rate 

constants for the oxidation reactions. Ultimately, the refined model will have the potential to be 

used to describe carbon–Hg–flue gas rates and equilibria for various kinds of carbons and to 

predict capture rates under a variety of conditions. Based on the developed models, capture rates 

for given sorbent loadings have increased. These embellishments to the sorbent comprise 

variations of the cation and anion structures in the oxidation site, but exact details cannot be 

revealed until patent protection has been acquired. 

References 

1. Huggins, R.E; Yap, N.; Huffman, G.P., Senior, C.L. Fuel Process. Technol. 2003, 82, 167. 

2. Miller, S.J.; Dunham, G.E.; Olson, E.S.; Brown, T.D. Fuel Process. Technol. 2000, 65B66, 

343B363. 

3. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Miller, S.J. Pavlish 

J.H. Prepr. Pap.CAm. Chem. Soc., Div. Fuel Chem. 2002, 47 (1), 481. 

4. Laumb, J.D.; Benson, S.A.; Olson, E.S. Fuel Process. Technol. 2004, 85 (6B7), 577B585. 

5. Ghorishi, S.B.; Keeney, R.M.; Serre, S.D.; Gullet, B.K.; Jozewicz, W.S. Environ. Sci. 

Technol. 2002, 36, 4454–4459. 

6. Rostam-Abadi, M.; Lu, Y.; Funk, C.; Richardson, C.; Paradis, J.; Chang, R. In Proceedings 

of Air Quality V: Mercury, Trace Elements, and Particulate Matter Conference; Arlington, 

VA. Sept 19–21, 2005. 

7. Granite, E.J.; Pennline, H.W.; Hargis, R.A. Ind. Eng. Chem. Res. 2000, 39, 1020–1029. 

8. Pavlish, J.H.; Holmes, M.J.; Benson, S.A.; Crocker, C.R.; Galbreath, K.C. In Proceeding of 

Air Quality III, Mercury, Trace Elements, and Particulate Matter Conference; Sept 9B12, 

2002. 

9. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Mibeck, B.A.; 

Miller, S.J.; Holmes, M.J.; Pavlish, J.H. An Improved Model for Flue GasBMercury 

Interactions on Activated Carbons. In Proceedings of the Combined Power Plant Air 

Pollution Control Mega Symposium; Washington, DC, May 19B22, 2003. 

10. Olson, E.S.; Crocker, C.R.; Benson, S.A.; Pavlish, J.H.; Holmes, M.J. J.AWMA, 2005, in 

press. 

11. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Miller, S.J.; Pavlish, 

J.P. Prepr. Pap.CAm. Chem. Soc., Div. Fuel Chem. 2003, 48 (1), 30B31. 
51 

12. Radovic, L.R.; Bockrath, B. Prepr. Pap.CAm. Chem. Soc., Div. Fuel Chem. 2002, 47 (2), 

428. 

13. Olson, E.S.; Mibeck, B.A.; Benson, S.A.; Laumb, J.D.; Crocker, C.R.; Dunham, G.E.; 

Sharma, R.K.; Miller, S.J.; Pavlish, J.H. Prepr. Pap.CAm. Chem. Soc., Div. Fuel Chem.

2004, 49. 

14. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Mibeck B.A.; 

Crocker, C.R.; Miller, S.J.; Holmes, M.J.; Pavlish, J.H. The Mechanistic Model for Flue 

GasBMercury Interactions on Activated Carbons. In Proceedings of the Air Quality IV: 

Mercury, Trace Elements, and Particulate Matter Conference; Arlington, VA, Sept 22B24, 

2003. 

15. Stock, A. US Patent 1,984,164, 1934. 

16. deJong, G.J.; Vos, H.J. US Patent 4,196,173. 

17. Nelson, S.G. US Patent Appl. 20040003716, 2004. 

18. Revoir, W.H.; Jones, J.A. US Patent 3,662,523, 1972. 

19. Bansal, R.C., Donnet, J-B.; Stoeckli, F. Active Carbon; Marcel Dekker: New York, 1988, 

259. 

20. Crocker, R.R.; Olson, E.S.; Mibeck, B.A. ; Sharma, R,K.; Benson, S.A.; Hill Brandt, K.L. In 

Proceedings of the 1st International Conference on Carbon for Energy Storage and 

Environment Protection; Orleans, France, Oct 2–6, 2005, p. 75. 
52 

HEALTH ASPECTS OF MERCURY EMISSIONS (QUARTER 5 REPORT) 

 Mercury released into the atmosphere from coal-fired power plants is deposited in the 

environment, becomes methylated, and accumulates in fish as they grow and age. Because of the 

higher methylmercury (CH3Hg) concentrations present in larger and older fish, consumption of 

these fish may be associated with health risks. This is of special concern in the case of prenatally 

exposed children. Although the dangers of acute exposures to high doses of Hg are well 

recognized, controversy over fish consumption and the actual risks of CH3Hg ingestion continue. 

Threshold levels for toxic effects of chronic exposure to low-dose Hg have not been possible to 

agree upon since no biochemical marker of risk has been established. However, insights into the 

physiological effects of Hg poisoning have the potential to reconcile these differences. 

 Dietary selenium’s ability to decrease the toxic action of Hg has been established in all 

investigated species of mammals, birds, and fish (1, 2). Since 1967, when the first report on the 

protective effect of Se against Hg toxicity appeared (3), numerous studies have shown that Se 

counteracts the negative impacts of Hg exposure. The Hg–Se interaction has previously been 

assumed to occur when supplemental Se complexes with Hg and prevents toxic effects in 

animals fed otherwise debilitating amounts of Hg (4–6). However, scientific understanding of 

this effect is rapidly changing. 

 Selenium is a nutritionally essential element required to support the activity of enzymes 

that are normally present in all cells of all creatures (7). Researchers are currently aware of 

25 selenoproteins, many of which are enzymes whose activities appear to be especially important 

in the brain, pituitary, and thyroid since these tissues are virtually impossible to deplete of Se 

(58). The selenide formed during each cycle of selenocysteine synthesis has an exceptionally 

high affinity constant for Hg: 1045—a millionfold higher than Hg’s affinity for sulfide: 1039 (8). 

 The high binding affinities between Se and Hg are clearly important in Se’s well-known 

protective effect against Hg toxicity. It has previously been assumed that Se’s protective effect 

was the result of Se-dependent binding of Hg, limiting its availability for causing harm in 

tissues. However, it is possible that instead of Se acting to immobilize Hg, Hg-dependent 

sequestration of Se could inhibit formation of selenium-dependent proteins. These proteins are 

normally present in all cells of all creatures. Since these enzymes are essential to support normal 

enzyme metabolic functions, especially in brain tissues, excessive exposure to Hg would be 

expected to disrupt selenium-dependent processes that occur in the brain. Hg-dependent 

sequestration of Se that leads to inhibition of selenium-dependent enzyme functions may explain 

why selenium-deficient rodents are more susceptible to prenatal toxicity of CH3Hg than those 

fed Se-adequate diets. This mechanism would also explain why maternal exposure to CH3Hg 

reduced Se-dependent enzyme activity in the brains of fetal/neonatal rats (9).

 The contrasting observations reported by studies of Hg exposure performed in fish-eating 

populations of the Seychelles and the Faroe Islands may be related to differences in Hg exposure 

relative to Se in the foods consumed by of their respective study populations. 

 In the Faroe Islands (10, 11), adverse associations from prenatal CH3Hg exposure have 

been found. Although adult Faroe Islanders consume ~72 g of fish a day, the fish they consume 
53 

have relatively low total Hg contents: ~0.07 ppm. However, less than 10% of the Hg they 

consume comes from fish. The pilot whale meat they eat is quite high in Hg and accounts for 

more than 90% of their mercury exposure. Averaged daily consumption of ~12-g portions of 

pilot whale muscle meat is much lower than that of fish, but whale meat is most often consumed 

in intermittent feasts with relatively large meal portions. With total Hg contents of 3.3 ppm 

(~50 times higher than the Hg of the fish they eat), pilot whale meat provides the bulk of Hg 

exposure in this population. The level of mercury-dependent harm found in Faroese children that 

have been prenatally exposed to Hg has been quite subtle, but distinct. 

 This is in contrast to the results of the Seychelles Study where no adverse associations 

have been noted, even though the absolute Hg exposure appears similar. A critical difference is 

that in the Seychelles, ~100% of the Hg exposure comes from fish consumption. The Seychelles 

population consumes large quantities of fish with relatively low Hg levels (12), resulting in a Hg 

exposure that is ~10–20 times as great as typically occurs in North American diets. In the 

Seychelles measurements of neurodevelopmental outcomes, fish consumption by Seychellois 

mothers during pregnancy was not associated with harmful effect but, in some cases, was 

associated with beneficial effects on their children, possibly as a result of improved nutrition 

(selenium and omega-3 fatty acid). 

 One explanation of the contrasting observations of the Faroe Islands and the Seychelles 

studies may be that they are observing dose-dependent differences that arise from intermittent 

exposures to high concentrations of Hg (characteristic of whale meat) as opposed to persistent 

low-level Hg exposures (characteristic of fish meat consumption). Another possibility that needs 

to be considered is that there are distinctions in the molar ratios of Hg and Se present in the 

foods consumed by their study populations. 

 Figure 8 shows the relative molar concentrations of Hg and Se present in fish and whale 

meats. The data displayed in Figure 8 were converted into molar concentrations in order to 

accurately compare Hg and Se contents in samples. Since 1 nmol Hg/g = 200.59 ppb; 1 ppm Hg 

=~5 nmol Hg/g; 1 nmol Se/g = 78.96 ppb, thus 1 ppm Se = ~12.6 nmol Se/g). Aside from pilot 

whale (13) and swordfish (14), data depicted in this figure originate from Hall et al. (15). 

 As is apparent in Figure 9, mercury is present at a ~fourfold excess in whale meat, but its 

relative abundance in fish is substantially less. Greater risks of maternal consumption causing 

neurodevelopmental harm in a developing fetus are associated with mercury occurring at molar 

ratios in excess of 1:1. Data shown were calculated from data displayed in Figure 8. 

 Fish samples collected from Minamata Bay contained as much as 40 ppm CH3Hg. 

Although Se contents were not measured in these fish, conservative estimates indicate the Hg:Se 

molar ratio in these fish would have been between 10 and 40 moles of Hg for every mole of Se. 

Children exposed in utero to Hg from these highly contaminated fish showed severe 

neurodevelopmental impairment, even though the mothers experienced minimal or no clinical 

symptoms (16).
54 

Figure 8. Molar relationships between mercury and selenium concentrations in seafood. 

Figure 9. Molar ratio of mercury:selenium concentrations in seafood.
55 

 The data shown in Figure 10 were calculated from data displayed in Figure 8. As is 

apparent in Figure 10, selenium is highly available in fish meat but very poorly available from 

whale meat. Selenium’s protective effects against Hg would be among the benefits associated 

with Se-rich dietary intakes from fish consumption. 

 The first panel in Figure 11 reflects the relative effects of mercury exposure from pilot 

whale vs. fish consumption in the Faroes. Since the concentration of mercury in pilot whale meat 

is ~50 times as great as that of the cod consumed in the Faroes, the slopes of the dose response 

curves of blood mercury levels are quite different. Blood MeHg rises quite rapidly for each meal 

of whale meat and is equaled only after many meals on fish. The graph reflects the approximated 

differences in exposure from whale feasts vs. normal fish meals. Because of the much greater 

time interval required to consume a similar quantity of MeHg, the natural depuration effects of 

exfoliation and hair growth diminish the intensity of the peak exposure from a similar mass 

quantity of MeHg from fish. Meanwhile, the second panel in Figure 11 depicts the relative 

effects of fish consumption vs. whale consumption on selenium status of the exposed individual. 

Each whale meal diminishes the selenium status of the consumer, meanwhile selenium status 

improves with each fish meal. 

 Recent work indicates the problem of excessive Hg exposure from whale meat consumption is 

not limited to the Faroes. Concentrations of MeHg in 160 samples of red meat products from small 

cetaceans sold for human consumption in markets throughout Japan from 2000–2003 all exceeded 

the provisional permitted levels in fish and shellfish set by the Japanese Government, 

Figure 10. Molar ratio of selenium:mercury concentrations in seafood. 
56 

Figure 11. Relative effects of whale vs. fish consumption. 

0.3 μg MeHg/wet g (17). The average MeHg level in the most contaminated species (false killer 

whale) was 11.5 μg MeHg/wet g. The molar ratio of total Hg to Se was substantially greater than 

1. It is, therefore, believed that consumption of red meat products from small cetaceans could 

pose a health problem for not only pregnant women but also for the general population. 

 It is clear that the Se naturally present in all foods and abundant in ocean fish and other 

seafoods can provide significant protection against Hg toxicity. However, it is becoming 

apparent that instead of merely being a protective “tonic,” Se is instead a potential “target” of Hg 

toxicity since the loss of Se-dependent enzymes undoubtedly contributes to Hg’s pathologic 

effects. As research on this issue accrues, it is apparent the tonic-to-target paradigm shift will 

foster new understanding of apparent discrepancies in results of various studies. Efforts to define 

interactions between Se and Hg continue to move forward as increasing numbers of research 

groups are investigating this emerging perspective of the Hg issue. 

Environmental Hg 

 Progress is being made in understanding how to deal with environmental Hg, and new 

practices may lead to ways of reducing Hg contamination of fish in freshwater lakes. Flooding of 

terrestrial areas stimulates MeHg production and leads to increased bioaccumulation in fish (18). 

Burning greatly reduced plant and soil retention of total and methylmercury, diminishing the 

amounts available for bioaccumulation in fish. Although this approach contributes to the global 

atmospheric pool of elemental Hg, it may be valuable to apply to reduce the Hg contamination in 

fish that often occurs in reservoirs and other areas where dry–wet cycling happens. 

 The Guizhou Province in the southwest of China has areas of extremely high soil selenium 

and also has many areas with high accumulations of Hg. Elemental analysis of a coal sample 

from this province indicated Hg concentrations of 55 ppm, which is ~200 times the average Hg 

concentration in North American coals (19). Atmospheric emissions of Hg from mining, ore 
57 

processing, chemical industry wastewaters, and coal burning for electricity production in 

Guizhou Province amount to ~12% of the world’s total anthropogenic emissions (20). As a 

result, even foods that are not normally known for mercury accumulation develop substantial and 

potentially hazardous burdens. The concentration of Hg in rice grains can reach up to 569 μg/kg 

of total Hg of which 145 μg/kg was in MeHg form. The percentage of Hg as MeHg varied from 

5% to 83%. Although this area is rich in Se, it is not known if the inorganic Hg in the rice is in 

the less available HgSe form or not. 

 Physical factors controlling total Hg and MeHg concentrations in lakes and streams of the 

northeastern United States were assessed using multiple regression models using watershed 

characteristics and climatic variables (21). These factors explained 38% or less of the variance in 

mercury values. Methylation efficiency (MeHg/total Hg) was modeled well (r2

 of 0.78) when a 

seasonal term was incorporated. Their physical models explained 18% of the variance in fish Hg 

concentrations in 134 lakes and 55% in 20 reservoirs. 

 The role of Se in reducing bioaccumulation of Hg in fish has been reported (22–24), and 

inverse relationships between fish tissue Hg and the abundance of Se present in the ecosystem 

have been noted (25, 26). Selenium supplementation of lake waters in Sweden resulted in a 

75%–85% reduction in Hg levels of fish over a 3-year period (27), and loss of Se can have the 

opposite effect. When Se-rich discharges of fly ash to an artificial lake were removed, 

researchers noted a steady increase in Hg concentrations (28, 29). Studies such as these indicate 

the importance of Se-dependent Hg retirement in aquatic ecosystems, possibly through formation 

of insoluble Hg:Se complexes that deposit in sediments. Several studies of the relationships 

between Hg and Se are currently ongoing in Canada and elsewhere in the world. 

References 

1. Grandjean, P.; Weihe, P.; White, R.F.; Debes, F. Cognitive Performance of Children 

Prenatally Exposed to “Safe” Levels of Methylmercury. Environ. Res. 1998, 77, 165–172. 

2. Beijer, K.; Jernelov, A. Ecological Aspects of Mercury–Selenium Interaction in the Marine 

Environment. Environ. Health Perspect. 1978, 25, 43–45. 

3. Parizek, J.; Ostadalova, I. The Protective Effect of Small Amounts of Selenite in Sublimate 

Intoxication. Experiential. 1967, 23 (2), 142–143. 

4. Culvin-Aralar, L.A.; Furness, R.W. Mercury and Selenium Interaction: A Review. 

Ecotoxicol. Environ. Saf. 1991, 21, 348–364. 

5. Suzuki, K.T. Equimolar Hg–Se Complex Binds to Selenoprotein P. Biochem. Biophys. Res. 

Commun. 1997, 231 (1), 7–11. 

6. Whanger, P.D. Selenium in the Treatment of Heavy Metal Poisoning and Chemical 

Carcinogenesis. J. Trace Elem. Electrolytes – Health Dis. 1992, 6 (4), 209–221. 
58 

7. Southworth, G.R.; Peterson, M.J.; Ryon, M.G. Long-Term Increased Bioaccumulation of 

Mercury in Largemouth Bass Follows Reduction of Waterborne Selenium. Chemosphere

2000, 41 (7), 1101–1105. 

8. Behne, D.; Pfeifer, H.; Rothlein, D.; Kyriakopoulos, A. Cellular and Subcellular 

Distribution of Selenium and Selenium-Containing Proteins in the Rat. In Trace Elements in 

Man and Animals 10; Roussel, A.M.; Favier, A.E.; Anderson, R.A., Eds.; Kluwer 

Academic/Plenum Publishers: New York, 2000; pp 29–34. 

9. El-Demerdash, F.M. Effects of Selenium and Mercury on the Enzymatic Activities and 

Lipid Peroxidation in Brain, Liver, and Blood of Rats. J. Environ. Sci. Health. 2001, 36 (4), 

489–499. 

10. Myers, G.J.; Davidson, P.W.; Cox, C.; Shamlaye, C.; Cernichiari, E.; Clarkson, T.W. 

Twenty-Seven Years Studying the Human Neurotoxicity of Methylmercury Exposure. 

Environ. Res. Section A. 2000, 83, 275–285. 

11. Grandjean, P.; Weihe, P.; White, R.F.; Debes, F.; Araki, S.; Murata, K. Cognitive Deficit in 

7-Year-Old Children with Prenatal Exposure to Methylmercury. Neurotoxicol. Teratol. 

1997, 19, 417–428. 

12. Iyengar, G.V.; Rapp, A.S.O. Human Placenta as a “Dual” Biomarker for Monitoring Fetal 

and Maternal Environment with Special Reference to Potentially Toxic Trace Elements. Part 

3: Toxic Trace Elements in Placenta and Placenta as a Biomarker for These Elements. Sci. 

Total Environ. 2001, 280 (1–3), 221–238. 

13. Julshamn K; Andersen A; Ringdal O; Morkore J. Trace Elements Intake in the Faroe 

Islands. I. Element Levels in Edible Parts of Pilot Whales (Globicephalus meleanus). Sci. 

Total Environ. 1987, 65, 53–62. 

14. Freeman, H. C.; Shum, G.; Uthe, J. F. The selenium content in swordfish (Xiphias gladius) 

in relation to total mercury content. J. Environ. Sci. Health, Part A: Environ. Sci. Eng. 1978, 

A13 (3), 235–40. 

15. Hall, R. A.; Zook, E. G.; Meaburn, G. M. National Marine Fisheries Service Survey of 

Trace Elements in the Fishery Resource. NOAA Tech. Rep., NMFS SSRF (1978) (NMFS 

SSRF-721), 313 pp. 

16. Tsubaki, T.; Irukayama, K. Minamata Disease: Methylmercury Poisoning in Minamata and 

Niigata, Japan. Tokyo: Kodansha Ltd. 1977, 57–95. 

17. Endo, Tetsuya; Haraguchi, Koichi; Hotta, Yohei; Hisamichi, Yohsuke; Lavery, Shane; 

Dalebout, Merel L.; Baker, C. Scott. Total Mercury, Methyl Mercury, and Selenium Levels 

in the Red Meat of Small Cetaceans Sold for Human Consumption in Japan. Environ. Sci. 

Technol. 2005, 39 (15), 5703–5708. 
59 

18. Mailman, M.; Bodaly, R. A. Total Mercury, Methylmercury, and Carbon in Fresh and 

Burned Plants and Soil in Northwestern Ontario. Environ. Pollut. (Amsterdam, Netherlands) 

2005, 138 (1), 161–166. 

19. Finkelman, R.B., Belkin, H.E., Zheng, B. Health Impacts of domestic coal use in China. 

Proc. Natl. Acad. Sci. 1999, 96, 3427–3431. 

20. Horvat, M.; Nolde, N.; Fajon, V.; Jereb, V.; Logar, M.; Lojen, S.; Jacimovic, R.; Falnoga, I.; 

Liya, Q.; Faganeli, J.; Drobne, D. Total Mercury, Methylmercury and Selenium in Mercury 

Polluted Areas in the Province Guizhou, China. Sci. Total Environ. 2003, 304 (1–3), 231–

256. 

21. Shanley, J.B.; Kamman, N.C.; Clair, T.A.; Chalmers, A. Physical Controls on Total and 

Methylmercury Concentrations in Streams and Lakes of the Northeastern USA. U.S. 

Geological Survey, Montpelier, VT, USA. Ecotoxicology 2005, 14 (1&2), 125–134. 

22. Boudou, A.; Ribeyre, F. Mercury in the Food Web: Accumulation and Transfer 

Mechanisms. In Metal Ions in Biological Systems: Mercury and Its Effects on Environment 

and Biology; Sigel, A.; Sigel, J., Eds.; Marcel Dekker: New York, 1997; pp 289–319. 

23. Jin, L.; Guo, P.; Xu, X. Effect of Selenium on Mercury Methylation in Faculative Lake 

Sediments. Toxicolog. Environ. Chem. 1999, 69 (1–2), 255–261. 

24. Bjoernberg, A.A. Decontamination of Mercury from Swedish “Black-Listed” Lakes by 

Addition of Selenium. In Proceedings of the 4th International Symposium of Uses of 

Selenium and Tellurium; Carapella, S.C. Jr., Ed.; Banff, Canada: Selenium-Tellurium Dev. 

Assoc., Darien, CT, 1989, pp 357–360. 

25. Chen, Y.W.; Belzile, N.; Gunn, J.M. Antagonistic Effect of Selenium on Mercury 

Assimilation by Fish Populations near Sudbury Metal Smelters. Limnol. Oceanogr. 2001, 46

(7), 1814–1818. 

26. Zhang, P.; Chen, C.; Zhao, J.; Li, B.; Xing, L.; Qu, L.; Chai, Z. Correlations of Mercury, 

Selenium, and Other Elements in Fish Tissues from the Regions at Different MercuryExposure Levels. In 7th International Conference on Mercury as a Global Pollutant; 

Pezdic, J., Ed.; Ljubljana, RMZ-Materials and Geoenvironment, 2004, 51, 1457–1460. 

27. Glass, G.E.; Sorenson, J.A.; Austin, J.J.; Schmidt, K.W.; Kallemeyn, L.W.; Hedman, S.C.; 

Rapp, G.R. Mitigating Mercury in Minnesota Lakes and Streams; Final Report to the 

 Minnesota Pollution Control Agency and Legislative Commission on Minnesota Resources; 

1995, pp 1991–1993. 

28. Paulsson, K.; Lindbergh, K. The Selenium Method for Treatment of Lakes for Elevated 

Levels of Mercury in Fish. Sci. Total Environ. 1989, 87–88, 495–507. 
60 

29. Southworth, G.R.; Peterson, M.J.; Turner, R.R. Changes in Concentrations of Selenium and 

Mercury in Largemouth Bass Following Elimination of Fly Ash Discharge to a Quarry. 

Chemosphere 1994, 29 (1), 71–79. 
61 

COMMERCIALIZATION ASPECTS OF SORBENT INJECTION TECHNOLOGIES IN 

CANADA (QUARTER 8 REPORT) 

 The CAMR in the United States and the acceptance in principle of a draft of the CWS for 

mercury illustrate the need for cost-effective mercury control strategies for coal-fired electric 

utilities. Recent demonstration activities have shown effective mercury capture with sorbent 

injection at full-scale systems. Out of this effort, concerns have been raised regarding the 

availability of carbon, sorbents, additives, and the related capital equipment if there were 

widespread adoption of ACI technology. 

 Issues that relate to the state of commercialization of sorbent injection technologies 

include the following: 

• Policy and regulatory issues that impact commercialization of mercury sorbent 

technologies 

• Sorbents most likely to be used based on coal type and plant configurations 

• Capital investment requirements and the availability of necessary equipment and labor 

• Availability of sorbents and/or additives 

• Status of mercury measurement technology for compliance purposes 

• Balance-of-plant impacts 

 Projections by the activated carbon industry do not suggest that either the availability of 

activated carbon or equipment will be a significant issue, although existing shortages in labor 

and construction materials are likely to continue, causing delays in capital improvements in 

Canada. Over the long term, there are several areas of concern that need to be addressed before 

widespread commercial implementation of sorbent injection technology can occur. These include 

the following: 

• Environmental and economic impacts of lost fly ash utilization (greenhouse gas credits) 

• The impact of ACI on FF and ESP performance 

• Environmental impacts of treated carbon 

• Longer-term leaching potential of disposed ash 

 A disadvantage of ACI is the impact the added carbon may have on ash salability. There 

are a large number of utilities in Canada and the United States that sell at least a portion of the 

ash collected to the concrete industry. In Canada, almost all the utilities burning lignite or 

subbituminous coal (SaskPower, TransAlta, EPCOR, and ATCO POWER) have facilities selling 

their ash for use as an admixture in place of portland cement at varying concentrations up to as 

high as 50%. A review of the impacts of mercury on by-product utilization was addressed in 

Quarter 4, Rerelease of Mercury from Coal Combustion By-Products, Therefore, any mercury 

control technology that prevents the sale of ash would have financial as well as environmental 

penalties. Increased ash to the landfill, forgone revenue from by-product sales, and increased 

energy consumption to manufacture portland cement not replaced with fly ash all directly result 

from activated carbon in fly ash. In some cases, as little as 1% carbon in the ash may result in 

rejection of the ash by the cement industry especially when from ACI. One method of preventing 
62 

activated carbon from entering the bulk of the fly ash is to add a small baghouse after the ESP 

with ACI between the two particulate control units. The downside is the added capital cost 

associated with installing a baghouse and the additional operating cost of replacing bags and the 

pressure drop. 

 The long-term effect of ACI injection on particulate control devices is currently being 

investigated. Long-term demonstration activities in Canada and the United States are being 

funded that will provide data over periods of up to 1 year. Data from these activities should help 

quantify many balance-of-plant effects, including both effects on particulate control devices and 

fate of halogens and other enhancement additives used to improve mercury capture. 

 Research is also ongoing to evaluate the long-term leaching potential of mercury from 

combustion by-products. Limited testing to date has indicated that mercury is stable on the ash; 

however, results from testing over periods of many months will be necessary to illustrate that 

stability. 
63 

UPCOMING EVENTS 

Power-Gen International 2005 Conference & Exhibition 

December 6–8, 2005, Sands Expo & Convention Center, Las Vegas, NV 

http://pgi05.events.pennnet.com 

Pittcon 2006 

March 12–17, 2006, Orlando, FL 

www.pittcon.org 

231st ACS National Meeting & Exposition 

March 26–30, 2006, Atlanta, GA 

www.chemistry.org 

Coal Ash Professionals Training Course 

April 19–21, 2006, Memphis, TN 

www.undeerc.org 

A&WMA Annual Conference & Exhibition 

June 20–23, 2006, New Orleans, LA 

www.awma.org 

Eighth International Conference on Mercury as a Global Pollutant 

August 6–11, 2006, Madison, WI 

www.mercury2006.org/Default.aspx?tabid+1393 

The Mega Meeting: Power Plant Air Pollutant Control Symposium (formerly The MegaSymposium) 

August 28–31, 2006, Baltimore, MD 

www.megasymposium.org 

Pittcon 2007 

March 11–16, 2007, New Orleans, LA 

www.pittcon.org 
64 

AUTHORS 

Dennis L. Laudal, Stanley Miller, Debra Pflughoeft-Hassett, Nick Ralston, Grant Dunham, and 

Greg Weber 

CONTACT INFORMATION 

For more information, please contact: 

 Michael J. Holmes 

 Deputy Associate Director for Research 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 mholmes@undeerc.org 

 (701) 777-5276 

 John H. Pavlish 

 Senior Research Advisor 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 jpavlish@undeerc.org 

 (701) 777-5268 

 Chad A. Wocken 

 Research Manager 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 cwocken@undeerc.org 

 (701) 777-5273 

 Dennis L. Laudal 

 Senior Research Advisor 

 Energy & Environmental Research Center 

 PO Box 9018 

 Grand Forks, ND 58202-9018 

 dlaudal@undeerc.org 

 (701) 777-5138 
APPENDIX D 

LABORATORY METHODS FOR THE 

EVALUATION OF POTENTIAL RELEASE OF 

MERCURY FROM COAL UTILIZATION BYPRODUCTS 
LABORATORY METHODS FOR THE 

EVALUATION OF POTENTIAL RELEASE OF 

MERCURY FROM COAL UTILIZATION 

BY-PRODUCTS 

Topical Report 

Prepared for: 

Ms. Lynn Brickett 

U.S. Department of Energy 

National Energy Technology Laboratory 

626 Cochrans Mill Road 

PO Box 10940 MS 922-273C 

Pittsburgh, PA 15236-0940 

Other Industrial Sponsors 

Prepared by: 

Debra F. Pflughoeft-Hassett 

David J. Hassett 

Tera D. Buckley 

Loreal V. Heebink 

Erick Zacher 

Energy & Environmental Research Center 

University of North Dakota 

PO Box 9018 

Grand Forks, ND 58202-9018 

April 2005
EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental 

Research Center (EERC), an agency of the University of North Dakota, as an account of work 

sponsored by the U.S. Department of Energy, Center for Air Toxic Metals®, Cynergy, Utility 

Solid Waste Activities Group, North Dakota Industrial Commission, and Great River Energy. 

Because of the research nature of the work performed, neither the EERC nor any of its 

employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement 

or recommendation by the EERC. 

DOE DISCLAIMER

 This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 

ACKNOWLEDGMENT

 This report was prepared with the support of the U.S. Department of Energy (DOE) 

National Energy Technology Laboratory Cooperative Agreement No. DE-FC21-93MC30098. 

However, any opinions, findings, conclusions, or recommendations expressed herein are those of 

the authors(s) and do not necessarily reflect the views of DOE. 
i 

TABLE OF CONTENTS 

LIST OF FIGURES ........................................................................................................................ ii 

EXECUTIVE SUMMARY ...........................................................................................................iii

INTRODUCTION .......................................................................................................................... 1 

BACKGROUND ............................................................................................................................ 1 

OBJECTIVES................................................................................................................................. 3 

METHODOLOGIES – ANALYTICAL AND CHARACTERIZATION METHODS ................. 4 

 Chemical and Physical Characterization ............................................................................... 4 

 Total Mercury ............................................................................................................... 4 

 Total Air Toxic Elements.............................................................................................. 4 

 Total Bulk Chemical Composition ............................................................................... 4 

 LOI and Moisture.......................................................................................................... 5 

 pH.................................................................................................................................. 5 

 Carbon Forms................................................................................................................ 5 

 Eh .................................................................................................................................. 5 

 Method Used to Measure Mercury on Gold-Coated Quartz Traps........................................ 5 

 Method Used to Measure Mercury on Carbotraps................................................................. 6 

METHODS FOR THE EVALUATION OF THE RELEASE POTENTIAL OF MERCURY 

AND OTHER AIR TOXIC ELEMENTS FROM CUB................................................................. 6 

 Direct Leaching...................................................................................................................... 6 

 Vapor-Phase Transport .......................................................................................................... 8 

 Long-Term Ambient Temperature Release .................................................................. 8 

 Vapor-Phase Transport ........................................................................................................ 10 

 Thermal Desorption at Elevated Temperature............................................................ 10 

 Microbiologically Mediated Leaching and Vapor-Phase Transport.................................... 13 

SUMMARY.................................................................................................................................. 16 

REFERENCES ............................................................................................................................. 17 

DRAFT ASTM STANDARD METHOD FOR SYNTHETIC GROUNDWATER 

LEACHING PROCEDURE ..........................................................................................Appendix A 
ii 

LIST OF FIGURES 

1 Information from EPA on mercury emissions........................................................................ 2 

2 Long-term leaching results for boron ..................................................................................... 7 

3 Indirect evidence of ettringite formation using SGLP and LTL............................................. 8 

4 Mercury vapor release collection apparatus ........................................................................... 9 

5 Average total long-term ambient-temperature mercury release or sorption as related 

to blank values ...................................................................................................................... 10 

6 Mercury thermal desorption apparatus ................................................................................. 11 

7 Typical thermal desorption curve for fly ash........................................................................ 12 

8 Example of thermal desorption curve for an FGD material ................................................. 12 

9 Microbiologically mediated mercury vapor-phase collection apparatus utilizing a 

wrist action shaker to facilitate mixing................................................................................. 14 

10 Microbiologically mediated mercury vapor-phase collection apparatus utilizing a 

stir plate to facilitate mixing ................................................................................................. 14 

11 Example of a SPME chromatogram ..................................................................................... 15 
iii 

LABORATORY METHODS FOR THE EVALUATION OF POTENTIAL RELEASE OF 

MERCURY FROM COAL UTILIZATION BY-PRODUCTS 

EXECUTIVE SUMMARY 

 Under a 3-year effort funded by the U.S. Department of Energy (DOE) and industry 

entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of coal utilization by-products (CUBs). 

The EERC is measuring the release of mercury and other air toxic elements under different 

controlled laboratory conditions and investigating the release of these same air toxic elements in 

select field settings. Results will be used to determine if mercury release from CUBs, both as 

currently produced and as produced with mercury and other emission controls in place, will 

potentially impact CUB management practices. In order to adequately address the potential for 

release of mercury from CUBs, sorbents, and combinations, release mechanisms that must be 

evaluated include 1) leaching, 2) elevated- and ambient-temperature vapor-phase releases, and 

3) microbiologically mediated releases. The EERC initiated research on the potential release of 

mercury from CUBs in 1999 and found that methodologies for evaluating the release of mercury 

from CUBs using these mechanisms were not documented in the scientific literature, with the 

exception of leaching. As a result, method development work was initiated under the U.S. 

Environmental Protection Agency (EPA) Center for Air Toxic Elements and the Coal Ash 

Resources Research Consortium. 

 The EERC concluded Year 2 of this effort in April 2005, and this report details the results 

to date from Task 2: Analytical Methods Selection. As noted in several forums in recent years, the 

methods used to evaluate CUBs must be relevant to the material and the management of CUBs 

where possible. EERC researchers reviewed methods currently being used at the EERC and 

elsewhere to determine the best possible methods for this effort. 

 Laboratory methods were selected based on early work performed at the EERC but method 

development and modification continued. The methods being employed to evaluate the release of 

mercury from CUBs by direct leaching, exposure to ambient and elevated temperatures, and 

exposure to biota are described, and method limitations are discussed. 
1 

LABORATORY METHODS FOR THE EVALUATION OF POTENTIAL RELEASE OF 

MERCURY FROM COAL UTILIZATION BY-PRODUCTS 

INTRODUCTION 

 The stability of mercury associated with coal utilization by-products (CUBs) has become a 

prominent question as the coal-fired utility industry develops and tests mercury emission controls 

that may consequently increase the mercury associated with CUBs. The reasons for evaluating 

the release of mercury from CUBs are 1) to determine if mercury captured on CUBs is stable or 

if it will be released, thus negating the purpose of the removal of the mercury from the 

emissions, and 2) to aid utilities in determining and understanding changes in CUBs associated 

with mercury control and associated CUB management. 

 Under a 3-year effort funded by the U.S. Department of Energy (DOE) and industry 

entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of CUBs. The EERC is measuring the 

release of mercury and other air toxic elements under different controlled laboratory conditions 

and investigating the release of these same air toxic elements in select field settings. Results will 

be used to determine if mercury released from CUBs, both as currently produced and as 

produced with mercury and other emission controls in place, will impact CUB management 

practices. 

 The EERC concluded Year 2 of this effort in April 2005, and this report details the results 

to date from Task 2: Analytical Methods Selection. As noted in several forums in recent years, the 

methods used to evaluate CUBs must be relevant to the material and the management of CUBs 

where possible. EERC researchers reviewed methods currently being used at the EERC and 

elsewhere to determine the best possible methods for this effort. A summary of research in this 

area was published in 2004 (1). 

BACKGROUND 

 Recent projections from the Energy Information Administration indicate that U.S. demand 

for energy will increase from 97.3 quadrillion to 130.1 quadrillion Btu between 2001 and 2020, 

reflecting an annual growth rate of 1.5%. By 2025, total energy consumption is projected to 

reach 139.1 quadrillion Btu (2). Fossil fuel combustion, including the burning of coal, natural 

gas, or oil, provides about 85% of the present energy production in the United States. Of this 

amount, over 50% is provided by coal-fired utilities (2). As a result of energy production from 

coal, CUBs are generated, and CUBs, as produced in the United States, are primarily a result of 

emission control technologies installed to meet emission regulations. 

 Emission regulations first mandated reduction of particulate matter released to the 

atmosphere by utilities, which required utilities to install collection devices for generated fly ash. 

Later emission regulations significant to CUB production mandated limits on SOx emissions. As 
2 

a result, utilities using high-sulfur coal could change coal sources, resulting in a different 

by-product character, or scrub the flue gas using sorbents to remove the SOx gases. The result of 

flue gas desulfurization (FGD) was high volumes of spent FGD sorbent material. There is a wide 

range of FGD technologies, so FGD materials have broadly varied characteristics, but generally 

contain high concentrations of calcium and sulfur. Currently, utilities are responding to 

regulation placing limits on NOx emissions, which also impacts the character of ash by-products, 

including potentially increasing the amount of unburned carbon in fly ash or adding ammonia to 

the fly ash. Issues related to air toxic emissions, including mercury, are currently under technical 

and regulatory scrutiny. 

 Figure 1 includes an excerpt from a U.S. Environmental Protection Agency (EPA) Fact 

Sheet titled “EPA Proposes Options for Significantly Reducing Mercury Emissions from Electric 

Utilities,” in which some of the concerns about mercury are summarized. On December 14, 

2000, EPA announced that it would regulate mercury emissions from coal- and oil-fired electric 

utility steam-generating power plants (3); propose regulations by December 15, 2003; and 

finalize regulations by December 15, 2004. On December 15, 2003, EPA signed the Utility 

Mercury Reductions proposal, which seeks comments on two approaches for reducing mercury 

by up to nearly 70%. On March 15, 2005, the EPA issued the first federal rule to permanently 

cap and reduce mercury emissions from coal-fired power plants (a power plant is defined as an 

electrical generating facility that provides >25 MWe). The rule is a market-based cap-and-trade 

program (Section 111 of the Clean Air Act) and is similar to the program in place for SO2. The 

rule is to be administered in two phases. The first phase places a cap of 38 tons per year of 

mercury beginning in 2010. The second phase sets a final cap of 15 tons by 2018. Coal-fired 

power plants currently emit about 48 tons per year; therefore, the reduction in mercury emissions 

will be 21% and 69%, respectively. 

Figure 1. Information from EPA on mercury emissions (4). 

Mercury Emissions – Both Naturally Occurring and Man-made Sources

• Mercury is a toxic, persistent pollutant that accumulates in the food chain. Fossil fuel-fired utilities are 

the largest source of human-generated mercury emissions in the United States. 

• Concentrations of mercury in the air are usually low and of little direct concern. However, 

atmospheric mercury falls to Earth through rain or snow and enters lakes, rivers, and estuaries. Once 

there, it can transform to its most toxic form, methylmercury, and accumulate in fish and animal 

tissues. 

• Americans are exposed to mercury primarily by eating contaminated fish. Because the developing 

fetus is the most sensitive to the toxic effects of mercury, women of child-bearing age are regarded as 

the population of greatest concern. Children who are exposed to low concentrations of methylmercury 

prenatally are at increased risk of poor performance on neurobehavioral tasks, such as those measuring 

attention, fine motor function, language skills, visual-spatial abilities, and verbal memory. 

EXCERPTED FROM EPA FACT SHEET: 

EPA Proposes Options for Significantly Reducing 

Mercury Emissions from Electric Utilities 

December 15, 2003 
3 

The reduction of emissions at coal-fired power plants has historically impacted the 

quantity and character of resulting CUBs. The removal or reduction of mercury emissions at 

coal-fired power plants has high potential to do the same because several proposed mercury 

emission control technologies involve the use of solid sorbents that will likely be introduced in 

the flue gas and collected with the fly ash. Other candidate emission control technologies focus 

on increasing the mercury sorbed on FGD materials. These mercury emission control 

technologies will impact the mercury content of CUBs. The question that this project was 

designed to answer is, “Will the changes in CUBs associated with mercury emission controls 

change the management options for those CUBs as they relate to the potential release of 

mercury?” 

Since the large volumes of CUBs produced annually in the United States are managed 

either by disposal or utilization, the design of various tasks in this project focused on simulating 

potential behavior of CUBs in environments where they are typically managed. Examples of 

utilization scenarios include: 

• The use of fly ash in concrete, soil stabilization, or fills that could be exposed to natural 

waters or to microbial action. 

• The use of FGD gypsum in wallboard, where it may be exposed to high temperatures in 

production or to natural water under disposal. 

• The use of fly ash in cement clinker production, where it would be exposed to 

extremely high temperatures. 

• The use of FGD gypsum or fly ash as an agricultural soil amendment or mine fill, where 

it would be exposed to natural water and, potentially, microbial action. 

 In order to adequately address the potential for release of mercury from CUBs, sorbents, 

and combinations, release mechanisms that must be evaluated include leaching, elevated- and 

ambient-temperature vapor-phase releases, and microbiologically mediated releases. The EERC 

initiated research on the potential release of mercury from CUBs in 1999 and found that methods 

for evaluating the release of mercury from CUBs using these mechanisms were not documented 

in the scientific literature, with the exception of leaching. As a result, the EERC initiated a 

program under EPA’s Center for Air Toxic Metals® and the Coal Ash Resources Research 

Consortium® to develop laboratory methods that would provide information on the potential for 

CUBs to release mercury and other air toxic elements under conditions associated with the 

proposed release mechanisms of direct leaching, direct ambient- and elevated-temperature vaporphase release, and microbiologically mediated leaching and vapor-phase release. 

OBJECTIVES 

The goal of the methods selection task was to select or develop appropriate laboratory 

methods to evaluate the potential for release of mercury from CUBs under conditions that are 

relevant to management options applied to CUBs. Supporting objectives were as follows: 
4 

$ Select and apply one or more leaching procedures appropriate for environmental 

characterization of CUBs. 

$ Select, develop, and apply a method to evaluate the release of mercury through 

offgassing from CUBs at elevated temperatures. 

$ Select, develop, and apply a method to evaluate the release of mercury through 

offgassing from CUBs exposed to ambient temperature air. 

$ Select, develop, and apply a method to evaluate the release of mercury through leaching 

and offgassing from CUBs exposed to biota commonly found in natural settings. 

$ Select and apply laboratory analytical methods required to determine mercury in 

solutions, collected on analytical traps, and in solid materials. 

METHODOLOGIES – ANALYTICAL AND CHARACTERIZATION METHODS 

Chemical and Physical Characterization 

Chemical characterization of samples included total mercury and total bulk chemical 

composition on major, minor, and trace constituents. Physical characterization included carbon 

forms, pH, moisture, and loss-on-ignition (LOI) measurements. Eh measurements were taken on 

samples used for microbiological experiments. Methodologies used for these characterizations 

are further described below. 

Total Mercury 

The total mercury content of solid samples was determined using a direct mercury analyzer 

or digestion followed by cold-vapor atomic absorption spectrometry (CVAAS). 

Total Air Toxic Elements 

The total concentration of the other air toxic elements of arsenic, cadmium, chromium, 

lead, nickel, and selenium was determined using standard methods. Acid digestion was used on 

the CUB followed by detection using inductively coupled atomic emission spectroscopy (ICP–

AES) or ICP mass spectroscopy (ICP–MS). 

Total Bulk Chemical Composition 

 The major bulk composition, reported as percent oxides, was determined using x-ray 

fluorescence spectrometry. American Society for Testing and Materials (ASTM) D4326-04 

Standard Test Method for Major and Minor Elements in Coal and Coke Ash by X-Ray 

Fluorescence was used (5). 
5 

LOI and Moisture 

Standard characterization techniques were used to measure LOI and moisture content. 

ASTM C311-04 Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans 

for Use in Portland-Cement Concrete was used (6). 

pH 

The pH of samples was determined using distilled water and/or 1 M KCl. The method 

employing 1 M KCl is required for many types of solid samples that exhibit a double electric 

layer that impacts the determination of pH. For this task, a slurry of 25 mL of 1 M KCl solution 

was mixed with 10 g of CUB, and the resulting pH was measured and recorded. As previously 

noted, the pH was also determined in slurry of distilled, deionized water. Where both methods 

were employed in this effort, it was noted that the pH values were similar. A comparison of these 

data for a relatively broad range of CUB types led researchers to conclude that it is not necessary 

to use 1 M KCl in determining the pH of CUB; therefore, remaining samples were evaluated 

using distilled, deionized water slurries. It is likely that the high concentration of total dissolved 

solids generated in the pH determination eliminated the double electric-layer effect that requires 

the use of KCl solution in the determination of pH in other types of solid samples. 

Carbon Forms 

Dominant carbon forms were identified in a select group of project samples. The samples 

on which carbon forms were determined were prepared by mounting them in epoxy resin. The 

sample was dispersed in the bottom of a 1-inch-diameter rubber cup mold. The epoxy was 

stained using Sudan black, which results in a high contrast between the particles of interest and 

the mounting medium. The surfaces to be analyzed were polished with incrementally smaller 

grits with 1⁄4 μm being the final polishing grit used. The samples were then examined using a 

reflected-light microscope.

Eh 

Eh was determined using a platinum electrode with a standard reference electrode. 

Method Used to Measure Mercury on Gold-Coated Quartz Traps 

Gold-coated quartz mercury collection traps were desorbed for analysis by heating to 

approximately 500°C, and the mass of mercury released was determined using double-gold 

amalgamation with atomic fluorescence (AF) detection. A Brooks Rand Model III cold-vapor 

atomic fluorescence spectrophotometer (CVAFS) was utilized for mercury concentration 

determination. 
6 

Method Used to Measure Mercury on Carbotraps 

Supelco CarbotrapTM collection traps were analyzed for total mercury by heating them to 

approximately 300°C, passing the released organomercury through a tube held at about 800°C, 

and collecting the mercury on a gold-coated quartz trap, which was analyzed as described above. 

METHODS FOR THE EVALUATION OF THE RELEASE POTENTIAL OF 

MERCURY AND OTHER AIR TOXIC ELEMENTS FROM CUB 

Direct Leaching 

 

 Leaching is the most likely mechanism of transport of constituents from disposed or 

utilized CUBs contacted by water. Leaching is typically performed on CUBs to characterize 

them for management purposes. The leaching tests performed on the samples in this project were 

the toxicity characteristic leaching procedure (TCLP [EPA Method 1311 (7)]), the synthetic 

groundwater leaching procedure (SGLP), and long-term leaching (LTL) with 30- and 60-day 

equilibration periods. 

TCLP is a leaching procedure designed for the evaluation of leaching of wastes when 

codisposed in a sanitary landfill. Leaching with TCLP utilizes a 20:1 liquid-to-solid ratio, endover-end agitation at approximately 30 rpm, an 18-hour equilibration time, and one of two 

extraction fluids. The extraction fluid used is dictated by the pH of the material being leached. 

Extraction Fluid 1, used when the pH is below 5, is prepared by adding glacial acetic acid and 

sodium hydroxide to reagent water, and has a fluid pH of 4.93 ± 0.05. Extraction Fluid 2, used 

when the pH of the material is above 5, is prepared by adding glacial acetic acid to reagent water, 

resulting in a fluid pH of 2.88 ± 0.05. 

 The SGLP batch-leaching procedure is a relatively simple test that follows many of the 

conditions of TCLP. The test utilizes a 20:1 liquid-to-solid ratio, end-over-end agitation at 

approximately 30 rpm, an 18-hour equilibration time, and usually employs a leaching solution 

consisting of water from the site, water that has been prepared in the lab similar to water likely to 

contact the CUB, or distilled deionized water. When distilled water is used as the leaching 

solution for SGLP, the method is equivalent to the ASTM D3987 Standard Test Method for 

Shake Extraction of Solid Waste with Water (8). Distilled deionized water was used in this 

effort. For the long-term component of this procedure, multiple bottles are set up and analyzed at 

different time intervals. A typical SGLP–LTL test might consist of 18-hour, 30-day, and 60-day 

equilibration times. Although 60 days is often not adequate to achieve complete equilibrium, it is 

generally long enough to determine the concentration evolution of individual parameters. The 

most important factor when performing LTL is to have at least three equilibration times to 

determine a true trend. A draft of the SGLP–LTL method prepared for consideration by ASTM is 

in Appendix A. 

 For all leaching procedures, the solids were filtered from the leaching solution through a 

0.45-μm filter, the pH of the resulting leachate was measured, and the leachate was preserved 

with HCl for mercury determination and with HNO3 for determination of other trace elements. 
7 

Mercury leachate concentrations were determined using CVAAS and CVAFS as noted in the 

analytical methods section. Other trace elements were determined using inductively coupled 

argon-plasma spectrometry, ICP–MS, or graphite furnace atomic absorption spectroscopy. 

 The SGLP method was used preferentially for the project samples, and where TCLP was 

applied, SGLP was also applied. TCLP was included because some regulatory groups continue 

to use TCLP results to determine whether a “waste” is hazardous. The SGLP short-term leaching 

procedure was applied to all samples, but for samples with a pH >10, the LTL option was also 

used. CUBs exhibiting a high pH have the potential to undergo hydration reactions that can 

change the leaching profile with time. The EERC documented the impact of ettringite formation 

on leachate concentrations of several elements that are frequently present in CUBs such as 

selenium and boron (9–12). The elements that are most likely to be incorporated into the 

ettringite structure and exhibit a change in leaching profile with time are those that are present as 

oxyanions at high pH. Examples of leaching profiles of high pH CUBs for some trace 

constituents commonly found in CUBs are shown in Figures 2 and 3. 

Figure 2. Long-term leaching results for boron.
8 

Figure 3. Indirect evidence of ettringite formation using SGLP and LTL (note: boron is on a 

secondary axis). 

Vapor-Phase Transport 

Long-Term Ambient Temperature Release 

In order to develop a method to evaluate the potential for release of mercury from CUBs at 

ambient temperatures, several preliminary decisions were made based on the practicality of 

performing this type of evaluation in the laboratory, as follows: 

• In order to measure mercury releases from CUBs, most of which have very low 

concentrations of mercury, samples with relatively high concentrations of mercury 

would be evaluated first. 

• In order to evaluate multiple samples with available equipment and instrumentation, 

released mercury would be collected on analytical gold-coated quartz traps. 

• Because very low release of mercury was anticipated, it was decided to expose a 

column of CUB to low-mercury air rather than expose only the surface of a CUB to the 

ambient temperature low-mercury air. 

 Using these preliminary premises, 250-mL wide-mouth glass test containers were designed 

with bonded Teflon liner caps. Two holes were drilled in the caps to accommodate a silicone 

tube for gas inlet and a Teflon outlet bulkhead fitting. The gas inlet tube extended nearly to the 

bottom of the container while the outlet tube extended only slightly into the container. 
9 

Using these test containers, approximately 150-g aliquots of CUB provided a column of 

material through which the low-mercury air could be transported. Breathing-quality air from a 

cylinder was passed through several sets of gold-coated quartz traps for mercury removal and 

admitted to each of the bottles through a gas distribution manifold that routed the gas through 

0.25-mm-ID gas chromatography (GC) capillary tubing to each of the individual bottles. The 

pressure drop across the GC capillary tubing allowed for the regulation of air flow through each 

bottle by simply adjusting the length of tubing to each bottle. The length of tubing was a nominal 

65 cm. This length of tubing, when pressurized to between 1 and 2 psig through a gas 

distribution manifold, provided a convenient means of regulating gas flow to approximately 

2 cm3

/min. Because of the variability of particle sizes between different ash samples, the sample 

with the initial highest gas flow was left with a 65-cm length of GC tubing, and other samples 

had their tubing lengths shortened until all samples had approximately the same flow rate. The 

air exiting the GC tubing was given a final scrubbing to remove mercury vapor using a goldcoated quartz trap just prior to entering the bottle containing the CUB. After entering the bottles, 

the air passed through the ash and exited to a central mercury collection tube containing two 

separate gold-coated quartz traps. The second outlet or top trap was used to prevent mercury 

contamination from atmospheric mercury. This setup is illustrated in Figure 4. 

The gold-coated quartz trap nearest the exit bulkhead fitting was analyzed multiple times 

with the most typical sampling scheme being one 7-day period followed by two consecutive 90-

day periods. The gold-coated quartz analytical traps were evaluated according to the method 

described in the analytical method section. In order to determine the total mercury released over 

the duration of the experiment, the mercury results from all experimental time segments needs to 

be combined, and the container blank needs to be subtracted. The container blank was 

determined on the empty bottles used to hold the samples. 

Figure 4. Mercury vapor release collection apparatus. 
10 

 Examples of replicate data from a variety of CUB samples are shown in Figure 5. 

Figure 5. Average total long-term ambient-temperature mercury release or sorption as related to 

blank values, pg/g/day. Positive values indicate release and negative values indicate sorption of 

mercury. 

Vapor-Phase Transport 

Thermal Desorption at Elevated Temperature 

 Since mercury and mercury compounds are highly volatile, mercury was expected to be 

released from CUBs when they were exposed to elevated temperatures. Even mercury that is 

sorbed on fly ash, FGD material, or sorbents developed to remove mercury in flue gas is 

expected to have high potential to be released if exposed to high enough temperatures. 

Instrumental and equipment constraints existed for the physical testing of elevated temperature 

release of mercury from CUBs. These constraints included the following: 

• Furnaces available for the experimental apparatus could only achieve maximum 

temperatures of 750°C. 

• Fittings and connecting tubing needed to be heated in order to minimize the loss of 

mercury in the system. 

• Gas flow to remove the mercury from the heated sample cell to the analytical cell 

needed to be constant. 

• Temperature ramping needed to be controlled and consistent between sample runs. 
11 

 The apparatus was constructed as shown in Figure 6. The CUB sample was weighed into a 

quartz tube with quartz wool used to keep the sample in place in the tube. Nominal sample size 

was approximately 1 g. The sample tube was placed into a small tube furnace capable of 

achieving a maximum of 750°C. A programmed temperature controller ramped the furnace from 

ambient to maximum temperature at 25°C per minute. In preliminary experiments, the maximum 

temperature achievable was 700°C, but an improved furnace was incorporated into the apparatus 

to increase the maximum to 750°C. A nitrogen gas flow of 5 cm3/min was introduced into the 

tube furnace. As the mercury and mercury compounds desorbed from the CUB in the sample 

tube, the nitrogen flow carried them though the system to the electrically heated quartz analytical 

cell. The quartz analytical cell was operated at 800°C, allowing the detection of mercury 

compounds by thermally decomposing compounds to form elemental mercury, which can be 

detected by atomic absorption (AA). The analytical cell at the top of the diagram was placed in 

the center-focused beam path of an AA spectrophotometer (AAS). A mercury hollow cathode 

lamp was used as the light source, and the AAS detector was set to the 253.7 nm line for 

mercury. A Hewlett Packard 3395 integrator was used for data collection. 

 Examples of thermal desorption curves generated with this method are shown in Figures 7 

and 8. 

Figure 6. Mercury thermal desorption apparatus. 
12 

Figure 7. Typical thermal desorption curve for fly ash. 

Figure 8. Example of thermal desorption curve for an FGD material. 
13 

Microbiologically Mediated Leaching and Vapor-Phase Transport 

The EERC review of published data on the release of mercury from CUBs (1) reported that 

the only published method demonstrated for use in evaluating the release of mercury from CUBs 

on exposure to natural biota was developed by the EERC. The EERC method has been under 

development since approximately 1999 and has undergone numerous modifications to achieve 

the goal of evaluating the mercury release potential by leaching and offgassing when CUBs are 

under microbiologically mediated conditions. The first experiments performed using early 

versions of the apparatus focused on mercury releases by offgassing. 

The first apparatus assembled to conduct microbiologically mediated vapor-phase mercury 

release used a 250-mL Erlenmeyer flask fitted with an impinger inlet/outlet tube with the inlet 

center shortened to 6 cm below the standard taper. Cylinder gas was passed through several sets 

of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas 

distribution manifold that routed the gas through 0.25-mm GC capillary tubing to each of the 

individual flasks. A GC capillary length of approximately 60 cm, when pressurized to between 

1 and 2 psig through a gas distribution manifold, provided a convenient means of regulating gas 

flow to approximately 2 cm3

/min. The gas passed mercury vapor from the head space of the 

flasks to a mercury vapor collection system at the outlet of the flasks, consisting of two traps. 

The nearest trap contained Supelco CarbotrapTM, which collected organomercury compounds, 

followed by a gold-coated quartz trap, which collected elemental mercury. 

The flasks were placed on a 16-flask wrist-action shaker. The experimental matrix 

consisted of eight flasks under anaerobic conditions (using argon) and eight flasks under aerobic 

conditions (using breathing-quality air). In each set of eight flasks, two contained only buffer, 

three contained the CUB with buffer (starved), and three contained the CUB with buffer and 

glucose (fed). An 80-g aliquot of CUB was placed in the flasks, and 100 mL of a phosphate 

buffer (with or without glucose as appropriate) was added to create a neutral pH. The CUBcontaining flasks also had 100 μL of mixed bacterial culture added. The source of bacteria was a 

mixed bacterial inoculum from a brackish wetland. This setup is illustrated in Figure 9. 

This apparatus underwent several iterations as difficulties were identified and solved. The 

wrist-action shaker was abandoned because it was unable to provide adequate suspended sample. 

Instead of the wrist-action shaker, a 9-place stir plate was introduced. This was operated for 

about 20 minutes every 3 hours to maintain sample agitation over the 30-day period of the 

experiment. Additionally, the sample size was reduced to 20 g, and the buffer was increased to 

150 mL to provide adequate sample volume for additional trace element analyses. The buffer 

composition was also altered. It was found that phosphate and nitrate interfered with a 

derivitization step in the determination of organomercury compounds in the solid-phase 

microextraction (SPME) determination using GC separation followed by detection of the 

mercury compounds by atomic fluorescence. This technique is described later. The original 

buffer utilized nominal concentrations of phosphate and nitrate salts. The improved buffer used 

only 100 ppm of phosphate and substituted potassium glutamate as the nitrogen source. This 

simple change appeared to remove the interferences. Additionally, later experiments did not 

involve the use of starved control samples. In current experiments, all samples are fed with 

glucose. This setup is illustrated in Figure 10. 
14 

Figure 9. Microbiologically mediated mercury vapor-phase collection apparatus utilizing a wrist 

action shaker to facilitate mixing. 

Figure 10. Microbiologically mediated mercury vapor-phase collection apparatus utilizing a stir 

plate to facilitate mixing. 
15 

Analyses of mercury and air toxic element releases were performed after a 30-day period. 

The gold-coated quartz traps and CarbotrapsTM were analyzed as described in the analytical 

methods selection. Total mercury concentrations of the leachate were determined using CVAFS. 

Total air toxic element concentrations were determined using ICP–AES or ICP–MS. 

Bacterial counts were performed upon completion of the experiment. A 1-mL aliquot of 

solution was taken from each flask. The aqueous supernate was serially diluted in 0.1% sodium 

pyrophosphate buffer (pH 7) and then used to inoculate a series of tubes containing 1% PTYG 

(peptone, tryptone, yeast extract, glucose) broth. The tubes were incubated at 30°C and growth, 

as turbidity, was monitored over a 3-week period. 

SPME was used in the determination of organomercury species in the liquid portions of the 

samples. SPME is a sample collection technique in our case utilizing a fiber coated with 

polydimethylsiloxane. Samples containing organomercury compounds are first derivatized to 

increase the volatility of organomercury halides such as methylmercuric chloride. The 

derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and 

sodium tetraphenyl borate. Sodium tetraethyl borate was most commonly used. In the 

derivitization procedure, derivatizing agent, acetate buffer, an internal standard (usually propyl 

mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, 

the halide is replaced with the appropriate alkyl or aryl group, depending on which derivatizing 

agent is chosen. A SPME fiber was inserted through the septum cap, and the sample was stirred 

using a Teflon-coated stir bar for 20 minutes. After this equilibration time, the SPME fiber was 

introduced into the heated inlet zone of a GC. Sample separation can be accomplished using a 

0.53-mm capillary column 15 or 30 meters in length. The exit end of the column was connected 

to a heated (800°C) quartz tube, and makeup helium gas was added to increase the total flow to 

25–30 mL per minute. The gas was then routed to an AF detector for determination of the 

separated mercury compounds. An example of a SPME chromatogram generated with this 

method is shown in Figure 11. 

Figure 11. Example of a SPME chromatogram. 
16 

SUMMARY 

 Analytical methods were selected based on project needs and the sample types requiring 

analysis. Standard analytical methods were selected and used as frequently as possible. Replicate 

analyses were performed on a regular basis as part of the laboratory quality assurance/quality 

control program. 

 The leaching method selected, the SGLP–LTL, was selected based on EERC experience 

and familiarity with a large number of leaching procedures used to characterize CUBs and the 

appropriate application of those tests. The SGLP–LTL meets the criteria that EERC researchers 

have identified for leaching procedures to provide scientifically valid information. These criteria 

are as follows: 

• Reactivity or other properties of the material being leached that may influence the 

leaching profile. 

• The setting where the material is to be placed and the water that will most likely contact 

that material in that setting. 

• The leaching time required to allow adequate time for hydration reactions to occur in 

reactive materials, such as high calcium coal fly ash. 

 The elevated-temperature vapor-phase release method underwent minor modifications 

early in the project but has been shown to provide reproducible data. The remaining technical 

challenge with the method as employed for this project is the limitations associated with the 

maximum achievable temperature to be applied to the CUB under investigation; and this cannot 

be addressed under this project. 

 The ambient-temperature vapor-phase release method developed for this work also presents 

technical challenges, but they are related to the quantitation limitations for mercury. The 

extremely low levels of mercury released at ambient temperatures are frequently near the levels 

of detection for the analytical system being used. The physical nature of the CUB samples also 

results in variable data and the need to modify the method. As an example, using the apparatus to 

evaluate the potential for release of mercury from a wet FGD material required modification of 

the apparatus to shorten the gas inlet tube to above the level of the sample because gas could not 

be forced through the material when the inlet was near the bottom of the sample container. 

 The method developed to evaluate the microbiologically mediated release of mercury 

underwent a relatively high degree of modification method over the first 2 years of the project. 

The final apparatus description and method now meets the project goals to produce reliable and 

relatively reproducible vapor and leachate samples. An evaluation of the particle-size reduction 

associated with the use of magnetic stir bars in the reaction vessels will be performed, and results 

of that evaluation will be included in future project reports. 
17 

REFERENCES 

1. Hassett, D.J.; Pflughoeft-Hassett, D.F.; Heebink, L.V. A Review of the Current State of the 

Science Related to Rerelease of Mercury from Coal Combustion Products; Final report for 

Utility Solid Waste Activities Group; EERC Publication 2004-EERC-11-01; Energy & 

Environmental Research Center: Grand Forks, ND, Nov 2004. 

2. Energy Information Administration. Annual Energy Outlook 2004 with Projections to 2025; 

U.S. Department of Energy: Washington, DC, 2004. 

3. Regulatory Finding on the Emissions of Hazardous Air Pollutants from Electric Utility 

Steam Generating Units. Fed. Regist. 2000, 65 (245), 79825–79831. 

4. U.S. Environmental Protection Agency. Fact Sheet “EPA Proposes Options for Significantly 

Reducing Mercury Emissions from Electric Utilities,” Dec 15, 2003. 

5. American Society for Testing and Materials. Standard Test Method for Major and Minor 

Elements in Coal and Coke Ash By X-Ray Fluorescence. D4326-04. 

6. American Society for Testing and Materials. Standard Test Methods for Sampling and 

Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete. C311-04. 

7. U.S. Environmental Protection Agency; Test Methods for Evaluating Solid Waste: 

Physical/Chemical Methods (SW-846), Method 1311, Toxicity Characteristic Leaching 

Procedure. 1992. 

8. American Society for Testing and Materials. Standard Test Method for Shake Extraction of 

Solid Waste with Water. In Annual Book of ASTM Standards; Section 11: Water and 

Environmental Technology, ASTM D3987-85, 2004. 

9. Hassett, D.J.; McCarthy, G.J.; Henke, K.R.; Korynta, E.D. Characterization of a Lignite Ash 

from the METC Gasifier III: Correlations with Leaching Behavior and Mineralogy. In Fly 

Ash and Coal Conversion By-Products: Characterization, Utilization, and Disposal I.; 

McCarthy G.J.; Lauf, R.J., Eds.; Materials Research Society: Pittsburgh, PA, 1985. 

10. Hassett, D.J.; Pflughoeft-Hassett, D.F.; McCarthy, G.J. Ettringite Formation in Coal Ash as 

a Mechanism for Stabilization of Hazardous Trace Elements. In Stabilization and Aquatic 

Uses, Proceedings of the 9th International Ash Use Symposium; Orlando, FL, Jan 22–25, 

1991; EPRI Report GS-7162, Project 3176, 1991; Vol. 2, pp 31-1–31-17. 

11. Hassett, D.J., Thompson, J.S. Ettringite Formation as a Fixation Technology for 

Immobilizing Trace Elements; Final Report to GRI GRI-96/0322. Feb 1997, 41 

12. McCarthy, G.J.; Hassett, D.J.; Bender, J.A. Synthesis, Crystal Chemistry and Stability of 

Ettringite, a Material with Potential Applications in Hazardous Waste Immobilization. In 

Proceedings of the Materials Research Society Symposium; 1992; Vol. 245.
APPENDIX A 

DRAFT ASTM STANDARD METHOD FOR 

SYNTHETIC GROUNDWATER LEACHING 

PROCEDURE
DRAFT

1 

DRAFT ASTM STANDARD METHOD FOR 

SYNTHETIC GROUNDWATER LEACHING PROCEDURE 

1. Scope 

1.1 This method determines the leachability of constituents in wastes, products, or materials 

using a leaching solution designed to simulate leachate anticipated in field conditions. 

The method allows for prediction of changes in leachability brought about as a result of 

the formation of secondary hydrated phases and new minerals through interaction of the 

waste and water over extended periods of time. 

1.2 his method consists of the agitation of waste and a synthetic groundwater solution over 

an extended period of time (greater than 60 days) with sampling at regular intervals. 

1.3 This method allows a comparison of maximum leachate concentration with actual 

concentrations of leachate at time intervals of from 18 hours to 2 months or greater. The 

method allows for determination of mass of analyte mobilized based on a leachate 

concentration and percent of total element leached and provides information to estimate 

leachate concentration trends with respect to time. 

1.4 This method may involve hazardous materials, operations, and equipment. This standard 

does not purport to address all of the safety problems associated with its use. It is the 

responsibility of whoever uses this method to consult and establish appropriate safety 

and health practices and determine the applicability of regulatory limitations prior to use. 

2. Applicable Documents 

2.1 American Society for Testing and Materials (ASTM) Standards: 

D1129 Definitions of Terms Relating to Water 

D1193 Specification for Reagent Water 

D3987 Shake Extraction of Solid Waste with Water 

D2216 Method for Laboratory Determination of Moisture Content of Soils 

2.2Toxicity Characteristic Leaching Procedure (TCLP) EPA Method 1311 

 

3. Definitions 

3.1 For definitions of terms in this test method, see Definitions D1129. 

3.2 Ettringite: Ettringite is a mineral having the nominal composition Ca6Al2(SO4)3(OH)12 

·26H2O. Ettringite is also the family name for a series of related compounds as is the 

case for many mineral families. Ettringite has characteristic structural features that are 

fairly unique. The structure comprises of calcium aluminate columns 

{Ca6Al2(OH)1224H2O}6+ with the channels between these columns containing the other 

components, which include an oxyanion such as sulfate with hydroxide and water 

{(SO4)2-4 (OH)0-4 (H2O)0-6}6-. Ettringite is unique in that several elements that exist as 

oxyanions can substitute for the sulfate in the structure. These elements include but are 

not limited to arsenic, boron, chromium, molybdenum, selenium, and vanadium. 

Ettringite is known to form in the hydration of low-rank coal conversion solid residues 
DRAFT

2 

(CCSRs) and in CCSRs from advanced coal combustion processes such as fluidized-bed 

combustion (FBC) and limestone injection modified burner (LIMB). 

3.3 Synthetic Groundwater: Synthetic groundwater as used in this application refers to a 

solution prepared in the laboratory containing the major geochemical parameters that 

would be found in water likely to contact the disposed CCSR. In the case of rainwater 

contact, this solution would be Type IV water, while with groundwater, a typical 

solution might contain calcium, magnesium, sodium, sulfate, and bicarbonate. 

Groundwater collected at the site of disposal could also be used, although if that were 

the case, corrections would have to be made for concentrations of trace elements already 

present in the water. It has been found with most CCSRs that it is the CCSR that 

regulates the equilibrium concentrations of major constituents in a synthetic groundwater 

leaching procedure; thus the inclusion of major geochemical constituents of actual 

groundwater may be unnecessary in many cases. 

4. Significance and Use 

4.1 This test is intended as a means for determining the mass of analyte readily mobilized by 

leaching with groundwater and also provides a means of determining the trend of 

leachate concentration change, if applicable. This test is intended for use with CCSRs 

and other materials formed under conditions of high temperature. The long-term nature 

of the test allows the determination of changes in concentrations of leached constituents 

as materials react with water to form secondary hydrated phases and other materials not 

present in the original material. 

4.2 This test method is not intended to provide an accurate means of determining actual 

leachate concentrations under field conditions. The test does provide information about 

leaching under field conditions, however, and is useful in predicting the mobility of 

leachable constituents of CCSRs. The information provided from this test is an 

estimation of the mass of analyte that can be solubilized and trend of concentration 

change with respect to time. It should be noted that not all analytes will increase in 

concentration to an equilibrium level. Numerous elements, especially those trace 

elements that exist as oxyanions in aqueous solution, can exhibit a decrease in solution 

concentration after an initial and normally rapid increase in concentration. Additionally, 

major constituents can change solution concentration in a manner that would not be 

predicted on the basis of solubility calculations based on common mineral types, 

especially in CCSRs that form ettringite. 

4.3 Since CCSRs are produced under conditions of high temperature, reactions with water 

during leaching can be expected. If these reactions produce ettringite, the concentrations 

of analytes present in solution as oxyanions can be expected to decrease with respect to 

time as ettringite forms. Other mineral formation can be expected to control leachate 

concentrations of additional analytes in ways not expected from simple solubility 

calculations based on the composition of ash before leaching. Additionally, the 

formation of secondary hydrated phases can be expected to affect the concentrations of 

major components. 
DRAFT

3 

5. Apparatus 

5.1 For a complete description of the apparatus, see ASTM Standard Test Method for Shake 

Extraction of Solid Waste with Water. Any apparatus that can provide conditions of endover-end agitation at 30 plus or minus 2 rpm as specified in the protocol for the TCLP 

can be used in this procedure. 

6. Reagents 

6.1 Purity of Reagents – Reagent-grade chemicals can be used, provided they do not contain 

appreciable amounts of elements to be determined in the extraction test. Reagents must 

be of sufficient purity so they do not interfere with the accuracy of the test or introduce 

bias in the results of analyses of leachates. 

6.2 Purity of Water – Unless otherwise indicated, references to water shall be understood to 

mean Type IV reagent water at 18° to 27°C (Specification D1193). The method by 

which the Type IV water is prepared (distillation, ion exchange, reverse osmosis, etc.) 

should remain constant throughout the test. 

6.3 Synthetic Groundwater – Synthetic groundwater is a leaching solution containing the 

major geochemical parameters important to groundwater likely to contact disposed 

CCSRs. As previously stated, in the case of CCSRs disposed above the water table and 

where the likely water to contact the disposed materials is rainwater, Type IV water can 

be used as the leaching solution. Where the water likely to contact disposed material is 

highly mineralized, either a sample of the water itself or a synthetic mixture prepared in 

the lab will be used. A typical North Dakota synthetic groundwater can be prepared by 

dissolving 0.50 grams of sodium sulfate and 1.00 grams of sodium bicarbonate in one 

liter of Type IV water. The analysis of this solution is as follows: 

Na 436 mg/L 

SO4 338 mg/L 

HCO3 726 mg/L 

pH 8.3–8.7 

This sodium sulfate bicarbonate buffered water is typical for central and western North Dakota. 

Used for leaching low-rank coal ash, calcium was omitted since the ash itself ultimately 

determined the final calcium concentration. 
DRAFT

4 

Other formulas for synthetic groundwater can be prepared as needed for site-specific 

conditions. Care is required when preparing formulations containing calcium and magnesium 

that carbonates not be allowed to precipitate. This can be overcome by adding the reagents in 

the proper order, being certain that all carbonate is buffered to bicarbonate before adding the 

calcium and magnesium. Since sulfuric acid is used for sulfate and acid buffering, having 

excess sulfuric acid acidity will ensure this. A lotus spreadsheet is available for the calculations 

necessary to select reagents for synthetic groundwater formulations, but with the limited 

components, the calculations can also be easily carried out manually. 

7. Sampling 

8. Sample Preparation 

8.1 For sample preparation, see D3987 Standard Test Method for Shake Extraction of Solid 

Waste with Water. 

9. Procedure 

 The laboratory protocol is similar to the U.S. Environmental Protection Agency (EPA) TCLP 

and ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water. The 

primary difference is in the selection and preparation of the extraction fluid and the extension of test 

equilibration time over the prescribed 18-hour period. The long-term leaching aspect of this test is 

especially important since CCSRs can form secondary hydrated phases upon contact with water that 

can have a profound impact on leachate concentration of trace elements, especially elements that tend 

to exist as oxyanions in solution. The formation of secondary hydrated phases is known to take time, 

depending on the source of reactants in the leaching system. Time for complete formation of 

secondary hydrated phases can be from days to months. The test is not intended to carry the leaching 

to complete equilibrium but rather to extend the leaching time long enough for prediction of leachate 

concentration trends. For specifics related to the test, see D3987 Standard Test Method for Shake 

Extraction of Solid Waste with Water, or EPA Method 1311 TCLP, Federal Register, Vol 55, No. 

126, June 29, 1990. 

9.1 Record the physical description of the sample to be tested including particle size as 

known. 

9.2 Solids Content – Determine the solids content of the sample as described in D3987 

Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.2.1 

through 9.2.4. 

9.3 Shake Procedure – Prepare the apparatus and begin the test as described in D3987 

Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.4 

through 9.7, except that multiple shake test containers are prepared for each sample, the 

number depending on the duration of long-term leaching. Leaching solution shall be 

prepared as described in the following section. Long-term leaching intervals for this 

procedure are 18 hours, 1 week, 1 month, and 2 months. Longer times can be used if 

desired, although trends are usually identified within the 60-day duration of this longterm leaching procedure. An alternative to the use of 2 liters of leaching solution 

involves the use of 225-mL polysulfone bottles. To each bottle, 10 grams (dry weight) of 

ash is added along with 200 mL of leaching solution. Multiple bottles prepared in this 
DRAFT

5 

manner provide at least 150 mL of leachate and allow for the simultaneous extraction of 

a large number of samples with minimal space and equipment. It has been found that the 

standard equipment used for TCLP leaching will generally hold four of the polysulfone 

containers in the same position usually reserved for one 2-liter container. 

9.4 Preparation of Leaching Solution: Leaching solution shall be prepared as recommended 

by an evaluation of field conditions. Where material disposed in a monofill is above the 

water table, the leaching solution shall be Type IV water (D1193 Specification for 

Reagent Water). Where the disposed material will likely be contacted by groundwater, 

either a sample of groundwater from the site or a synthetic groundwater shall be used for 

leaching. The synthetic groundwater if prepared in the lab shall contain all of the 

primary mineralization parameters as determined from an analysis of groundwater from 

the site or from an evaluation of data from analysis reports of water representative of the 

area of disposal. 

9.5 Long-Term Leaching Sampling B Long-term samples are taken from containers prepared 

for the shake test in an identical manner to the specimen for the 18-hour sampling 

period. These containers are sampled at the end of 1 week, 1 month, and 2 months. 

Longer sampling intervals can be added as required. A convenient method for doing this 

procedure is to prepare the samples at time intervals so that all of the samples are 

finished at the same time. For example, one sample is prepared, a second is prepared 1 

month later, a third sample 1 month later, and a final sample 18 hours before the other 

samples are due to be terminated. This saves considerable lab time and expedites the 

entire procedure. 

9.6 Sampling of Leachate B Leachate is sampled for analysis as specified in D3987 Standard 

Test Method for Shake Extraction of Solid Waste with Water, Section 9.8. 

9.7 Analysis 

9.7.1 Selection of Analytes to Be Included in the Report. Analytes include all elements 

present in the ash in high enough concentrations to be problematic in disposal. 

These can be determined through screening procedures such as proton-induced 

x-ray emission (PIXE), instrumental neutron activation analysis (INAA), or 

plasma emission such as inductively coupled argon plasma (ICAP) spectroscopy 

or ICAP–mass spectrometry. Analytes for ash screening generally include the 

eight Resource Conservation and Recovery Act (RCRA) elements for regulatory 

purposes. 

9.7.2 Determination of Total Concentration of Select Analytes. Analytes selected on 

the basis of screening (9.6.1) are determined on a bulk sample prepared by 

digestion of sample in a microwave heated-sealed Teflon bomb. Analyses can be 

performed according to methods for trace analyses in SW846. 

9.7.3 Determination of Analyte Concentrations in Leachates. Concentrations of 

analytes in leachates shall be determined using methods as described in SW846 

or by approved analytical techniques using EPA or other approved techniques. 
DRAFT

6 

All data shall be validated using good laboratory practice and approved quality 

assurance/quality control (QA/QC) procedures. 

10. Calculation 

10.1 Calculate the solids content as specified in D3987 Standard Test Method for Shake 

Extraction of Solid Waste with Water, Section 10.1. 

10.2 Calculation of maximum analyte concentration is determined by dividing the total mass 

of analyte in a sample by the volume of liquid used for leaching. C = M/V where 

C = Concentration of analyte 

M = Mass of sample leached 

V = Volume of leaching solution used 

For this procedure the M:V ratio should be 1:20 as specified in the leaching protocol. 

11. Report 

11.1 The report shall include the following: 

11.1.1 Source of CCSR, date of sampling, and preservation method used for leachates. 

11.1.2 Description of CCSR including coal source, combustion technique, and method 

of sample collection (electrostatic precipitator, baghouse, etc.) 

11.1.3 Solids content (see Method D2216) 

11.1.4 A table of maximum analyte concentrations as determined by the method 

described in Section 10.2. (bulk chemical analysis) 

11.1.5 A table of analyte concentrations as determined from analysis of 18-hour, 1-

week, 1-month, 2-month, and any additional extended time intervals selected. 

12. Precision and Bias 

12.1 No information is presently available on the precision and accuracy or bias of this 

standard practice. It is recommended that standard QA/QC procedures such as analysis 

of duplicate samples and spiking of analyte be used for verification. 

12.2 The precision of this test will vary depending on the material being leached. 
APPENDIX E 

SAMPLE PRIORITIZATION 
Working Document Revised April 20, 2003 

1

Mercury and Air Toxic Element Impacts of Coal Combustion 

Byproduct Disposal and Utilization

Sample Selection Criteria EERC Priority Justification 

 (H=high; M=medium; 

 L=low) 

 FUEL TYPES 

• Bituminous H commonly used 

• Subbituminous H commonly used 

• Lignite H commonly used but 

 generally higher mercury 

 content 

• Oil H Industry sponsor priority 

• Bituminous–Subbituminous Blends H M limited use 

• Subbituminous–Lignite Blends L Only very limited use 

 BURNER TYPES 

• pc fired H Most common 

• Cyclone M Limited installations 

• Stoker L Limited installations 

• FBC L Limited utility installations 

PARTICULATE COLLECTION 

• Fabric Filter H commonly used 

• ESP Cold Side H Most common 

• ESP Hot Side M Less common 

• ESP/Mechanical L Limited installations 

• FF/Mechanical L Limited installations 

SO2 CONTROL 

• None H Most common 

• Wet FGD (calcium based) H Commonly used 

 (include lime & limestone sorbents; forced oxidation & natural or in situ 

 oxidation systems.) 

• Dry FGD (calcium based) M Less common 

• Spray Dryer Atomizer (SDA) H Commonly used with 

 potential for additional installations 

• Wet FGD (alkali based) L Limited installations 

• Dry FGD (alkali based) L Limited installations 

AMMONIA-BASED SYSTEMS 

• None H Most common 

• Ammonia Injection H Commonly used 

• SCR H Commonly used 

• SNCR H L Limited installations 

 
Working Document Revised April 20, 2003 

2

Mercury and Air Toxic Element Impacts of Coal Combustion 

Byproduct Disposal and Utilization (continued)

Sample Selection Criteria EERC Priority Justification 

 (H=high; M=medium; 

 L=low) 

PROPOSED Hg CONTROL 

• Carbon Injection H Predicted for high use 

• Noncarbon Sorbent Injection H Good potential for 

 limited impact to ash quality 

• Modified FGD H Expected to concentrate 

 mercury on FGD material and limit 

 impact to fly ash quality 

• Fine Particulate Control H Good potential for 

 limited impact to ash quality 

• Fly ash from carbon removal technologies H High interest to sponsors 

 
APPENDIX F 

SAMPLE IDENTIFICATION NUMBER AND 

DESCRIPTIONS 
ID No.

Collection 

Date Sample Type Sample Type Notes Sample Treatment Coal Type Coal Notes

Burn

Typ

99-188 2/9/1999 FGD-SDA PRB Subbituminous pc-fir00-048 10/12/2000 FGD-SDA Fort Union Lignite Cyclo01-002 2/26/2001 Fly Ash Eastern Bituminous pc-fir01-008 4/5/2001 Fly Ash PRB Subbituminous pc-fir01-011 5/9/2001 FGD-SDA Fort Union Lignite Cyclo02-002 4/25/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fir

02-003 4/26/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fir

02-004 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fir02-005 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fir02-006 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fir02-007 4/25/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fir

02-069 7/18/2002 Fly Ash + Activated Carbon Eastern Bituminous Low S pc-fir02-070 7/18/2002 Fly Ash Eastern Bituminous Low S pc-fir02-071 7/22/2002 Fly Ash + Activated Carbon Eastern Bituminous Low S pc-fir02-072 7/22/2002 Fly Ash Eastern Bituminous Low S pc-fir02-073 7/6/2002 Fly Ash Eastern Bituminous Low S pc-fir02-074 7/6/2002 Fly Ash Eastern Bituminous Low S pc-fir02-076 9/24/2002 Fly Ash

South American 

Bituminous Low S pc-fir

03-004 Fly Ash Eastern Bituminous KY & WV; Low S pc-fir03-005 Fly Ash Eastern Bituminous KY & WV; Low S pc-fir03-006 Fly Ash Eastern Bituminous KY & WV; Low S pc-fir03-007 Fly Ash Eastern Bituminous KY & WV; Low S pc-fir03-008 11/19/2002 Fly Ash

South American 

Bituminous Low S pc-fir

03-009 11/20/2002 Fly Ash + Activated Carbon

South American 

Bituminous Low S pc-fir

03-010 11/22/2002 Fly Ash + Activated Carbon

South American 

Bituminous Low S pc-fir

03-016 6/10/2003 Fly Ash Fort Union Lignite pc-fir03-017 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir03-018 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir03-019 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir03-060 5/21/2003 Fly Ash + Activated Carbon PRB Subbituminous

Belle Ayr coal; 6109 

tons/day coal + 94 tons/day 

waste seed corn: 98.5% 

coal/1.5% biomass Cyclo

03-061 5/10/2003 Fly Ash PRB Subbituminous 6400 tons/day coal Cyclo

03-062 6/10/2003 Fly Ash + Activated Carbon

lab composite of 03-017 – 

03-019 (80/10/10 wt%) Fort Union Lignite pc-fir

Page 1 of 8
ID No.

99-188 00-048 01-002 01-008 01-011 02-002 02-003 02-004 02-005 02-006 02-007 02-069 02-070 02-071 02-072 02-073 02-074 02-076 03-004 03-005 03-006 03-007 03-008 03-009 03-010 03-016 03-017 03-018 03-019 03-060 03-061 03-062 

Mercury Control

Mercury Control 

Configuration

Paired Mercury 

Control Sample

Low NOx 

Burner (LNB) SO2 Control

SO2 Control 

Description

Ammonia-Based 

System

No No FGD-dry calcium Lime spray dryer No

No No FGD-dry Spray dryer Unknown

No LNB No UnknownNo LNB No UnknownNo No FGD-dry Spray dryer Unknown

Activated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection Post-Primary PCD LNB No No

Activated Carbon Injection Pre-Primary PCD No No NoActivated Carbon Injection Pre-Primary PCD No No NoActivated Carbon Injection Pre-Primary PCD No No No

Activated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection Post-Primary PCD

Hg control test 

sample of 02-070

LNB w/ 

overfire air No No

No Baseline of 02-069

LNB w/ 

overfire air No No

Activated Carbon Injection Post-Primary PCD

Hg control test 

sample of 02-072

LNB w/ 

overfire air No No

No Baseline of 02-071

LNB w/ 

overfire air No No

No

LNB w/ 

overfire air No No

No

LNB w/ 

overfire air No No

No

Baseline of 03-009, 

03-010 LNB No SNCR

No LNB No SCRNo LNB No SCRNo LNB No SCRNo LNB No SCRNo LNB No

SNCR: Ureabased

Activated Carbon Injection Pre-Primary PCD

Hg control test 

sample of 02-076 LNB No

SNCR: Ureabased

Activated Carbon Injection Pre-Primary PCD

Hg control test 

sample of 02-076 LNB No

SNCR: Ureabased

No No No No

Activated Carbon Injection No No NoActivated Carbon Injection No No NoActivated Carbon Injection No No No

Fine Particulate Control + 

Activated Carbon Injection

Hg control test 

sample of 03-061 No No No

Fine Particulate Control Baseline of 03-060 No No No

Activated Carbon Injection No No No

Page 2 of 8
ID No.

Collection 

Date Sample Type Sample Type Notes Sample Treatment Coal Type Coal Notes

Burn

Typ

03-063 10/2/2003 Fly Ash Eastern Bituminous High S OH pc-fir03-065 10/2/2003 FGD Gypsum Eastern Bituminous High S OH pc-fir03-067 10/2/2003 FGD Slurry

dewatered with Büchner 

funnel 05/03/05 – resulting 

liquid saved as 03-103 Eastern Bituminous High S OH pc-fir

03-078 10/30/2002 Fly Ash Fort Union Lignite Cyclo03-079 10/30/2002 Fly Ash Fort Union Lignite Cyclo03-080 10/30/2002 Fly Ash Fort Union Lignite Cyclo03-081 10/30/2002 Fly Ash Fort Union Lignite Cyclo03-082 11/18/2003 FGD Filtercake

dewatered – resulting liquid 

saved as 03-104 Eastern Bituminous pc-fir

03-083 11/18/2003 Fly Ash Eastern Bituminous pc-fir03-084 11/18/2003 Fixated FGD

portion ground & dried at 

<40°C for microbiological 

experiment Eastern Bituminous pc-fir

03-085 11/18/2003 Fly Ash Eastern Bituminous pc-fir03-086 11/18/2003 FGD Filtercake

water poured off 1/18/06 – 

resulting liquid saved as 03-

114 Eastern Bituminous pc-fir

03-087 11/18/2003 Fixated FGD Eastern Bituminous pc-fir03-088 Fly Ash Eastern Bituminous pc-fir03-089 FGD Gypsum Eastern Bituminous pc-fir

03-103 10/2/2003 Lab dewatered FGD liquor

lab dewatered 03-067: 

FGD slurry Eastern Bituminous High S OH pc-fir

03-104 11/18/2003 Lab dewatered FGD liquor

lab dewatered 03-082: 

FGD filtercake Eastern Bituminous pc-fir

03-114 Lab dewatered FGD liquor

lab dewatered 03-086: 

FGD filtercake Eastern Bituminous pc-fir

04-003 6/28/2002 Fly Ash Eastern Bituminous WV, KY, & PA; Low S pc-fir04-004 6/28/2002 Fly Ash Eastern Bituminous WV, KY, & PA; Low S pc-fir04-006 11/1/1999 Fly Ash Western Bituminous CO pc-fir04-007 5/22/2003 Fly Ash Western Bituminous UT pc-fir04-029 Fly Ash PRB Subbituminous pc-fir

04-030 11/17/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir04-031 11/18/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir04-032 11/20/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir

Page 3 of 8
ID No.

03-063 03-065 03-067 03-078 03-079 03-080 03-081 03-082 03-083 03-084 03-085 03-086 03-087 03-088 03-089 03-103 03-104 03-114 04-003 04-004 04-006 04-007 04-029 04-030 04-031 04-032 

Mercury Control

Mercury Control 

Configuration

Paired Mercury 

Control Sample

Low NOx 

Burner (LNB) SO2 Control

SO2 Control 

Description

Ammonia-Based 

System

No No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium

Lime with fly ash 

recycle No

No No FGD-wet calcium

Lime with fly ash 

recycle No

No No FGD-wet calcium

Lime with fly ash 

recycle No

No No FGD-wet calcium

Lime with fly ash 

recycle No

No No FGD-wet calcium Limestone sorbents SCRNo No FGD-wet calcium Limestone sorbents SCRNo No FGD-wet calcium Limestone sorbents SCRNo LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium

Limestone-forced 

oxidation

SCR & Ammonia 

Injection

No LNB FGD-wet calcium

Limestone-forced 

oxidation

SCR & Ammonia 

Injection

No No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Limestone sorbents SCRNo LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No No No NoNo No No NoNo No No NoNo

LNB w/ 

overfire air FGD-wet calcium Limestone sorbents No

No LNB No

Ammonia 

Injection

Activated Carbon Injection Post-Primary PCD LNB FGD-wet calcium

Lime-natural or in situ 

oxidation No

Activated Carbon Injection Post-Primary PCD LNB FGD-wet calcium

Lime-natural or in situ 

oxidation No

Activated Carbon Injection Post-Primary PCD LNB FGD-wet calcium

Lime-natural or in situ 

oxidation No

Page 4 of 8
ID No.

Collection 

Date Sample Type Sample Type Notes Sample Treatment Coal Type Coal Notes

Burn

Typ

04-033 11/20/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fir04-035 3/24/2004 Fly Ash Fort Union Lignite pc-fir04-036 4/27/2004

Fly Ash + Enhancing Agent + 

Activated Carbon Fort Union Lignite pc-fir

04-042 5/11/2004 Fly Ash Gulf Coast Lignite Unkno04-043 5/11/2004 Fly Ash Gulf Coast Lignite Unkno04-044 5/11/2004 Fly Ash Gulf Coast Lignite Unkno04-045 5/11/2004 Fly Ash Gulf Coast Lignite Unkno04-054 11/18/2003 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fir

04-067 5/21/2004

Fly Ash + Enhancing Agent + 

Activated Carbon Fort Union Lignite pc-fir

04-082 8/19/2004 FGD Gypsum Eastern Bituminous pc-fir

04-083 11/8/2004 FGD Gypsum Eastern Bituminous pc-fir

05-001 2/2/2005 Fly Ash Fort Union Lignite pc-fir05-002 2/2/2005 FGD-SDA Fort Union Lignite pc-fir

05-003 2/24/2005

Fly Ash + Enhancing Agent + 

Activated Carbon Fort Union Lignite pc-fir

05-004 2/24/2005

FGD-SDA + Enhancing 

Agent + Activated Carbon Fort Union Lignite pc-fir

05-005 3/17/2005 Fly Ash Fort Union Lignite Cyclo05-009 7/19/2005 FGD Gypsum Eastern Bituminous High S Ohio pc-fir05-010 7/19/2005 Fly Ash Eastern Bituminous High S Ohio pc-fir

05-011 7/19/2005 FGD Gypsum Filtrate Eastern Bituminous High S Ohio pc-fir05-013 4/16/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir05-017 4/13/2005 Fly Ash + Enhancing Agent Fort Union Lignite Cyclo05-018 8/17/2005 Fly Ash Eastern Bituminous pc-fir05-019 8/17/2005 FGD Filtercake

water poured off 9/21/05 & 

solid pressed – resulting 

liquid saved as 05-032 Eastern Bituminous pc-fir

05-020 8/17/2005 Fixated FGD Eastern Bituminous pc-fir05-022 8/17/2005 FGD Filtrate Eastern Bituminous pc-fir05-023 5/14/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir

Page 5 of 8
ID No.

04-033 04-035 04-036 04-042 04-043 04-044 04-045 04-054 04-067 04-082 04-083 05-001 05-002 05-003 05-004 05-005 05-009 05-010 05-011 05-013 05-017 05-018 05-019 05-020 05-022 05-023 

Mercury Control

Mercury Control 

Configuration

Paired Mercury 

Control Sample

Low NOx 

Burner (LNB) SO2 Control

SO2 Control 

Description

Ammonia-Based 

System

Activated Carbon Injection Post-Primary PCD LNB FGD-wet calcium

Lime-natural or in situ 

oxidation No

No Baseline of 04-036

LNB w/ 

overfire air No No

Activated Carbon Injection + 

Enhancing Agent Injection Pre-Primary PCD

Hg control test 

sample of 04-035

LNB w/ 

overfire air No No

No LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents No

Activated Carbon Injection Post-Primary PCD LNB No No

Activated Carbon Injection + 

Enhancing Agent Injection

Enhancing Agent on 

Coal, ACI Pre-Primary 

PCD

LNB w/ 

overfire air No No

No No FGD-wet calcium

Limestone-forced 

oxidation SCR

No No FGD-wet calcium

Limestone-forced 

oxidation No

No Baseline of 05-003 No FGD-dry Spray dryer No

No Baseline of 05-004 No FGD-dry Spray dryer No

Activated Carbon Injection + 

Enhancing Agent Injection

Enhancing Agent on 

Coal, ACI before SDA

Hg control test 

sample of 05-001 No FGD-dry Spray dryer No

Activated Carbon Injection + 

Enhancing Agent Injection

Enhancing Agent on 

Coal, ACI before SDA

Hg control test 

sample of 05-002 No FGD-dry Spray dryer No

No Baseline of 05-017 No FGD-wet calcium

Lime with fly ash 

recycle No

No No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime No

Activated Carbon Injection Post-Primary PCD

Hg control test 

sample of 05-038 No No No

Enhancing Agent Injection

Enhancing Agent on 

Coal

Hg control test 

sample of 05-005 No FGD-wet calcium

Lime with fly ash 

recycle No

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

Activated Carbon Injection

Post-Primary PCD: 

High fly ash content

Hg control test 

sample of 05-038 No No No

Page 6 of 8
ID No.

Collection 

Date Sample Type Sample Type Notes Sample Treatment Coal Type Coal Notes

Burn

Typ

05-024 5/29/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir05-025 8/23/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir05-032 Lab dewatered FGD liquor

lab filtered 05-019: 

FGD filtercake Eastern Bituminous pc-fir

05-038 10/18/2005 Fly Ash Fort Union Lignite pc-fir05-040 11/1/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir06-001 11/17/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fir

Page 7 of 8
ID No.

05-024 05-025 05-032 05-038 05-040 06-001 

Mercury Control

Mercury Control 

Configuration

Paired Mercury 

Control Sample

Low NOx 

Burner (LNB) SO2 Control

SO2 Control 

Description

Ammonia-Based 

System

Activated Carbon Injection Post-Primary PCD

Hg control test 

sample of 05-038 No No No

Activated Carbon Injection

Post-Primary PCD: 

High fly ash content

Hg control test 

sample of 05-038 No No No

No LNB FGD-wet calcium Limestone sorbents

SCR & Ammonia 

Injection

No

Baseline of 05-013, 

05-023, 05-024, 05-

025, 05-040, 06-001 No No No

Activated Carbon Injection Post-Primary PCD

Hg control test 

sample of 05-038 No No No

Activated Carbon Injection Post-Primary PCD

Hg control test 

sample of 05-038 No No No

Page 8 of 8
APPENDIX G 

TOTAL TRACE ELEMENTAL DATA 
ID No. Sample Type Mercury Control Configuration Coal Type As (μg/g) Cd (μg/g) Cr (μg/g) Pb (μg/g) Hg (μg/g) Ni (μg/g

99-188 FGD-SDA PRB Subbituminous 14.7 <1 26.3 37 0.112 12.9 02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 55.602-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 32.002-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.0902-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 5.0002-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 37.4 1.97 111 60.2 5.81 50.6 02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 60.502-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 12002-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.74202-070 Fly Ash Eastern Bituminous 0.19002-070 Fly Ash Eastern Bituminous 0.19702-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.97502-072 Fly Ash Eastern Bituminous 0.16302-073 Fly Ash Eastern Bituminous 0.23402-074 Fly Ash Eastern Bituminous 0.61302-076 Fly Ash

South American 

Bituminous 0.607

03-004 Fly Ash Eastern Bituminous 72.2 <1 142 65.4 0.097 68.3 03-005 Fly Ash Eastern Bituminous 71.4 <1 148 72.6 0.084 85.7 03-006 Fly Ash Eastern Bituminous 78.0 1.36 135 94.3 0.194 60.4 03-007 Fly Ash Eastern Bituminous 68.6 1.13 138 89.0 0.141 55.2 03-007 Fly Ash Eastern Bituminous 72.1 <1 135 72.4 87.4 03-008 Fly Ash

South American 

Bituminous 0.151

03-016 Fly Ash Fort Union Lignite 33.7 <1 59.6 25.6 0.016 59.5 03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.1 <1 57.7 30.4 0.225 56.5 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 54.7 <1 61.5 40.4 0.289 54.0 03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 73.9 <1 64.8 47.4 2.22 51.4 03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 19.4 1.87 76.7 82.2 1.86 67.6 03-061 Fly Ash PRB Subbituminous 37.8 1.78 44.2 58.1 0.578 79.0 03-061 Fly Ash PRB Subbituminous 49.2 1.52 76.1 62.1 10703-061 Fly Ash PRB Subbituminous 43.4 1.86 82.4 58.4 95.8 03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 43.3 <1 54.4 30.3 0.490 57.6 03-063 Fly Ash Eastern Bituminous 45.5 <1 128 37.1 <0.1 23.3 03-065 FGD Gypsum Eastern Bituminous <1 <1 2.90 <3 <0.1 <1 03-067 FGD Slurr

y Eastern Bituminous 0.120

03-067 FGD Slurr

y Eastern Bituminous 0.196 

03-067 FGD Slurr

y Eastern Bituminous <1 <1 6.61 <3 <0.1 2.87

03-078 Fly Ash Fort Union Lignite 0.66203-079 Fly Ash Fort Union Lignite 351 2.1 83.2 68.3 0.785 40.9 03-080 Fly Ash Fort Union Lignite 157 1.06 66.1 39.9 0.440 63.5 03-081 Fly Ash Fort Union Lignite 492 3.60 85.2 124 0.459 68.4 03-082 FGD Filtercake Eastern Bituminous <1 <1 10.4 <3 0.218 3.50 03-082 FGD Filtercake Eastern Bituminous 0.248 03-083 Fly Ash Eastern Bituminous 163 3.48 134 258 252 03-083 Fly Ash Eastern Bituminous 169 3.66 139 272 0.017 266 03-084 Fixated FGD Eastern Bituminous 53.4 1.24 53.6 80.3 0.180 87.2 03-085 Fly Ash Eastern Bituminous 145 2.55 124 247 0.034 277 03-086 FGD Filtercake Eastern Bituminous <1 <1 10.2 4.40 0.162 3.98 03-087 Fixated FGD Eastern Bituminous 53.8 1.08 51.6 86.7 0.136 98.7 03-088 Fly Ash Eastern Bituminous 44 8.59 160 249 0.010 74.5 

Page 1 of 2
ID No. Sample Type Mercury Control Configuration Coal Type As (μg/g) Cd (μg/g) Cr (μg/g) Pb (μg/g) Hg (μg/g) Ni (μg/g

03-089 FGD Gypsum Eastern Bituminous <1 1.89 4.13 <3 <0.1 <1 03-089 FGD Gypsum Eastern Bituminous 0.09604-003 Fly Ash Eastern Bituminous 49.8 <1 138 60.4 77.2 04-003 Fly Ash Eastern Bituminous 42.2 <1 132 60.5 0.685 75.9 04-004 Fly Ash Eastern Bituminous 31.5 <1 144 55.7 0.041 81.6 04-006 Fly Ash Western Bituminous 5.90 <1 43.8 38.8 0.144 26.1 04-007 Fly Ash Western Bituminous 7.09 <1 64.9 29.1 0.521 22.0 04-029 Fly Ash PRB Subbituminous 31.1 1.07 63.7 38.6 0.261 39.9 04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 136 3.34 92.8 85.3 0.147 24.2 04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 134 3.24 91.8 83.4 0.174 28.2 04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 161 3.38 94.8 74.9 0.470 40.0 04-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 148 2.91 86.5 74.9 1.43 29.1 04-035 Fly Ash Fort Union Lignite 36.0 <1 55.4 21.9 0.159 17.2 04-036 

Fly Ash + Activated Carbon + 

Enhancing Agent

Enhancing Agent on Coal, ACI 

Pre-Primary PCD Fort Union Lignite 43.4 <1 48.4 18.3 0.287 23.1 

04-036 

Fly Ash + Activated Carbon + 

Enhancing Agent

Enhancing Agent on Coal, ACI 

Pre-Primary PCD Fort Union Lignite 46.3 <1 49.1 19.1 23.8 

04-042 Fly Ash Gulf Coast Lignite 0.37104-043 Fly Ash Gulf Coast Lignite 0.68904-044 Fly Ash Gulf Coast Lignite 0.87804-045 Fly Ash Gulf Coast Lignite 0.84904-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 444 1.16 115 49.0 17.7 94.5 04-067 

Fly Ash + Activated Carbon + 

Enhancing Agent

Enhancing Agent on Coal, ACI 

Pre-Primary PCD Fort Union Lignite 26.8 <1 44.8 25.9 0.640 41.5 

04-082 FGD Gypsum Eastern Bituminous 1.65 <1 3.39 <3 0.043 6.83 04-083 FGD Gypsum Eastern Bituminous <2 <1 3.95 <3 0.103 6.81 05-001 Fly Ash Fort Union Lignite 24.4 <1 45.1 17.4 <0.01 30.3 05-002 FGD-SDA Fort Union Lignite 22.6 <1 42.8 18.6 <0.01 29.7 05-003 

Fly Ash + Activated Carbon + 

Enhancing Agent

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 28.6 <1 45.5 21.2 0.565 25.7 

05-004 

FGD-SDA + Activated 

Carbon + Enhancing Agent

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 21.8 <1 37.3 20.9 0.332 25.3 

05-005 Fly Ash Fort Union Lignite 0.43105-009 FGD Gypsum Eastern Bituminous 0.03205-010 Fly Ash Eastern Bituminous 0.08005-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 38.6 <1 36.5 73.2 39.0 15.4 05-017 Fly Ash + Enhancing Agent Enhancing Agent on Coal Fort Union Lignite 0.717

05-018 Fly Ash Eastern Bituminous 0.12305-019 FGD Filtercake Eastern Bituminous 0.30505-020 Fixated FGD Eastern Bituminous 0.24905-023 Fly Ash + Activated Carbon

Post-Primary PCD: High fly ash 

content Fort Union Lignite 48.3 <1 42.6 87.1 12.7 18.6 

05-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 42.5 <1 35.5 82.2 35.9 17.6 05-025 Fly Ash + Activated Carbon

Post-Primary PCD: High fly ash 

content Fort Union Lignite 46.8 <1 39.1 84.7 12.6 20.4 

05-038 Fly Ash Fort Union Lignite 43.4 <1 43.4 90.1 0.104 21.1 05-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 38.4 <1 42.2 74.5 44.5 22.0 06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 35.3 <1 40.5 71.2 64.5 20.6 06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 35.6 <1 39.0 72.7 20.5 

Page 2 of 2
APPENDIX H 

FGD LIQUOR TOTAL TRACE ELEMENTAL 

CONCENTRATION AND pH DATA 
ID No. Sample Type Sample Type Notes Coal Type As (μg/L) Cd (μg/L) Cr (μg/L) Pb (μg/L) Hg (μg/L) Ni (μg/

03-103 

Lab dewatered 

FGD liquor

lab dewatered 03-067: 

FGD slurry

Eastern 

Bituminous 114 0.79 10.1 <2 <0.15 258 

03-104 

Lab dewatered 

FGD liquor

lab dewatered 03-082: 

FGD filtercake

Eastern 

Bituminous 54.4 2.89 2.9 <2 <0.15 333 

03-114 

Lab dewatered 

FGD liquor

lab dewatered 03-086: 

FGD filtercake

Eastern 

Bituminous 121 4.34 4.3 <2 NT 123 

05-011 

FGD Gypsum 

Filtrate

Eastern 

Bituminous 82.8 4.79 9.9 <2 <0.01 338 

05-032 

Lab dewatered 

FGD liquor

lab filtered 05-019: 

FGD filtercake

Eastern 

Bituminous 33.1 2.09 5.7 <2 NT 88.8 

Page 1 of 2
ID No. Sample Type Sample Type Notes Coal Type

Sample 

Prep

10–15-Min 

pH

10–15-Min 

pH Date 24-H

03-103 Lab dewatered FGD liquor

lab dewatered 03-067: 

FGD slurry Eastern Bituminous 6.73 5/3/2005

03-103 Lab dewatered FGD liquor

lab dewatered 03-067: 

FGD slurry Eastern Bituminous filtered 6.75 5/3/2005

03-103 Lab dewatered FGD liquor

lab dewatered 03-067: 

FGD slurry Eastern Bituminous 6.78 6/21/2006 7

03-104 Lab dewatered FGD liquor

lab dewatered 03-082: 

FGD filtercake Eastern Bituminous 6.53 5/3/2005

03-104 Lab dewatered FGD liquor

lab dewatered 03-082: 

FGD filtercake Eastern Bituminous filtered 6.73 5/3/2005

03-114 Lab dewatered FGD liquor

lab dewatered 03-086: 

FGD filtercake Eastern Bituminous 6.99 6/15/2006 7

03-114 Lab dewatered FGD liquor

lab dewatered 03-086: 

FGD filtercake Eastern Bituminous 7.36 8/1/2006 7

05-011 FGD Gypsum Filtrate Eastern Bituminous 5.44 5/8/2006 505-011 FGD Gypsum Filtrate Eastern Bituminous 5.40 8/1/2006 505-022 FGD Filtrate Eastern Bituminous 7.26 5/8/2006 805-022 FGD Filtrate Eastern Bituminous 7.20 8/1/2006 805-032 Lab dewatered FGD liquor

lab filtered 05-019: FGD 

filtercake Eastern Bituminous 6.75 6/13/2006 7

05-032 Lab dewatered FGD liquor

lab filtered 05-019: FGD 

filtercake Eastern Bituminous 6.63 8/1/2006 5

Page 2 of 2
APPENDIX I 

TOTAL BULK CHEMICAL COMPOSITION DATA, 

REPORTED AS OXIDES 
ID No. Sample Type

Mercury Control

Configuration Coal Type SiO2 (%) Al2O3 (%) Fe2O3 (%) CaO (%) MgO (%) Na2O (%) K2O (%) TiO2 (%) 

99-188 FGD-SDA

PRB 

Subbituminous 30.79 17.69 3.54 25.68 2.93 1.65 0.48 0.59 

03-004 Fly Ash

Eastern 

Bituminous 55.23 27.48 6.37 1.44 0.78 0.37 2.47 1.62 

03-005 Fly Ash

Eastern 

Bituminous 55.29 27.51 5.84 1.54 0.91 0.41 2.59 1.64 

03-006 Fly Ash

Eastern 

Bituminous 55.83 27.51 6.65 1.34 0.96 0.41 2.57 1.66 

03-007 Fly Ash

Eastern 

Bituminous 54.88 27.62 5.77 1.32 0.90 0.33 2.60 1.64 

03-016 Fly Ash Fort Union Lignite 44.19 15.87 7.34 17.67 5.56 4.39 1.61 0.60 03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.46 15.24 7.59 19.38 6.62 4.79 1.33 0.58 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 38.71 15.64 6.54 19.95 6.80 5.02 1.37 0.60 03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 35.23 14.87 5.63 18.86 6.38 5.12 1.31 0.57 03-060 Fly Ash + Activated Carbon Pre-Primary PCD

PRB 

Subbituminous 30.07 17.63 5.87 27.50 6.11 2.42 0.68 1.35 

03-061 Fly Ash

PRB 

Subbituminous 22.64 17.25 6.87 31.56 8.48 2.99 0.49 1.21 

03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.30 15.61 7.31 19.37 5.95 4.91 1.32 0.58 03-063 Fly Ash

Eastern 

Bituminous 41.01 18.78 32.46 2.88 0.72 0.41 1.58 0.96 

03-065 FGD Gypsum

Eastern 

Bituminous 0.39 0.05 0.03 34.69 0.91 0.00 0.01 0.02 

Page 1 of 1
APPENDIX J 

MOISTURE CONTENT AND LOI DATA 
ID No. Sample Type

Hg Control 

Configuration Coal Type

Moisture 

Content, % LOI, %

99-188 FGD-SDA PRB Subbituminous 1.18% 2.07%

02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 5.56% 22.2%

02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.07% 24.2%

02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 2.92% 19.4%

02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 2.59% 19.3%

02-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.53% 2.84%

02-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.72% 4.14%

02-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.07% 3.88%

02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.63% 23.9%

02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.99% 24.3%

02-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.86% 12.6%

02-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.69% 12.6%

02-070 Fly Ash Eastern Bituminous 0.24% 5.88%

02-070 Fly Ash Eastern Bituminous 0.15% 5.85%

02-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 1.18% 17.2%

02-072 Fly Ash Eastern Bituminous 0.13% 5.18%

02-072 Fly Ash Eastern Bituminous 0.21% 5.39%

02-073 Fly Ash Eastern Bituminous 0.14% 5.00%

02-074 Fly Ash Eastern Bituminous 0.36% 6.27%

02-074 Fly Ash Eastern Bituminous 0.22% 6.09%

02-076 Fly Ash

South American 

Bituminous 0.60% 21.1%

02-076 Fly Ash

South American 

Bituminous 0.44% 21.0%

03-004 Fly Ash Eastern Bituminous 0.12% 3.48%

03-004 Fly Ash Eastern Bituminous 0.15% 3.20%

03-005 Fly Ash Eastern Bituminous 0.17% 3.59%

03-005 Fly Ash Eastern Bituminous 0.18% 3.60%

03-006 Fly Ash Eastern Bituminous 0.18% 5.28%

03-006 Fly Ash Eastern Bituminous 0.21% 5.19%

03-006 Fly Ash Eastern Bituminous 0.12% 5.24%

03-007 Fly Ash Eastern Bituminous 0.15% 4.54%

03-007 Fly Ash Eastern Bituminous 0.19% 4.41%

03-008 Fly Ash

South American 

Bituminous 0.15% 12.7%

03-009 Fly Ash + Activated Carbon Pre-Primary PCD

South American 

Bituminous NT NT

03-010 Fly Ash + Activated Carbon Pre-Primary PCD

South American 

Bituminous NT NT

03-016 Fly Ash Fort Union Lignite 0.05% 0.34%

03-016 Fly Ash Fort Union Lignite 0.04% 0.24%

03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.06% 0.96%

03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.10% 1.23%

03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.12% 1.17%

03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.09% 0.97%

03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.61% 4.21%

03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.18% 2.47%

03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.15% 2.28%

03-061 Fly Ash PRB Subbituminous 0.19% 1.00%

03-061 Fly Ash PRB Subbituminous 0.14% 1.08%

Page 1 of 3
ID No. Sample Type

Hg Control 

Configuration Coal Type

Moisture 

Content, % LOI, %

03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.10% 1.29%

03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.02% 1.26%

03-063 Fly Ash Eastern Bituminous 0.06% 0.47%

03-065 FGD Gypsum Eastern Bituminous 25.7% 1.22%

03-067 FGD Slurry Eastern Bituminous 56.8% 4.37%

03-067 FGD Slurry Eastern Bituminous 65.7% 6.38%

03-078 Fly Ash Fort Union Lignite 0.48% 1.47%

03-079 Fly Ash Fort Union Lignite 0.28% 2.54%

03-080 Fly Ash Fort Union Lignite 0.45% 7.48%

03-081 Fly Ash Fort Union Lignite 0.68% 1.15%

03-082 FGD Filtercake Eastern Bituminous 28.9% 5.04%

03-082 FGD Filtercake Eastern Bituminous 40.0% 4.20%

03-082 FGD Filtercake Eastern Bituminous 28.6% 4.86%

03-083 Fly Ash Eastern Bituminous 0.15% 1.20%

03-084 Fixated FGD Eastern Bituminous 26.6% 3.17%

03-084 Fixated FGD Eastern Bituminous 27.1% 3.11%

03-085 Fly Ash Eastern Bituminous 0.16% 2.10%

03-086 FGD Filtercake Eastern Bituminous 43.3% 5.87%

03-087 Fixated FGD Eastern Bituminous 31.3% 3.80%

03-087 Fixated FGD Eastern Bituminous 31.9% 4.17%

03-088 Fly Ash Eastern Bituminous 0.17% 1.07%

03-089 FGD Gypsum Eastern Bituminous 21.6% 1.94%

04-003 Fly Ash Eastern Bituminous 0.16% 8.46%

04-003 Fly Ash Eastern Bituminous 0.24% 8.44%

04-004 Fly Ash Eastern Bituminous 0.13% 1.38%

04-004 Fly Ash Eastern Bituminous 0.11% 1.38%

04-006 Fly Ash Western Bituminous 0.17% 1.42%

04-007 Fly Ash Western Bituminous 0.08% 2.56%

04-007 Fly Ash Western Bituminous 0.05% 2.46%

04-029 Fly Ash PRB Subbituminous 0.14% 0.48%

04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.14% 0.76%

04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.13% 0.62%

04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.11% 0.67%

04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.18% 0.59%

04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.11% 1.09%

04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.40% 0.93%

04-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.43% 1.39%

04-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.22% 1.27%

04-035 Fly Ash Fort Union Lignite 0.19% 2.45%

04-035 Fly Ash Fort Union Lignite 0.16% 2.68%

04-035 Fly Ash Fort Union Lignite 0.06% 2.24%

04-036 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on 

Coal, ACI PrePrimary PCD Fort Union Lignite 0.05% 2.49%

04-036 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on 

Coal, ACI PrePrimary PCD Fort Union Lignite 0.07% 2.16%

04-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.60% 18.6%

Page 2 of 3
ID No. Sample Type

Hg Control 

Configuration Coal Type

Moisture 

Content, % LOI, %

04-067 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on 

Coal, ACI PrePrimary PCD Fort Union Lignite 0.06% 2.11%

04-082 FGD Gypsum Eastern Bituminous 26.5% 1.60%

04-083 FGD Gypsum Eastern Bituminous 26.6% 2.26%

05-001 Fly Ash Fort Union Lignite 1.00% 0.90%

05-002 FGD-SDA Fort Union Lignite 1.08% 0.95%

05-003 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on 

Coal, ACI before 

SDA Fort Union Lignite 0.85% 1.04%

05-004 

FGD-SDA + Enhancing 

Agent + Activated Carbon

Enhancing Agent on 

Coal, ACI before 

SDA Fort Union Lignite 0.75% 1.12%

05-005 Fly Ash Fort Union Lignite 0.02% 1.29%

05-009 FGD Gypsum Eastern Bituminous 26.1% 1.92%

05-010 Fly Ash Eastern Bituminous 0.33% 2.05%

05-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.29% 13.2%

05-017 Fly Ash + Enhancing Agent

Enhancing Agent on 

Coal Fort Union Lignite 0.05% 1.70%

05-018 Fly Ash Eastern Bituminous 0.04% 3.01%

05-019 FGD Filtercake Eastern Bituminous 33.3% 6.19%

05-020 Fixated FGD Eastern Bituminous 31.1% 3.65%

05-023 Fly Ash + Activated Carbon

Post-Primary PCD: 

High Ash Fort Union Lignite 0.13% 3.84%

05-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.23% 9.45%

05-025 Fly Ash + Activated Carbon

Post-Primary PCD: 

High Ash Fort Union Lignite 0.13% 3.20%

05-025 Fly Ash + Activated Carbon

Post-Primary PCD: 

High Ash Fort Union Lignite 0.00% 3.18%

05-038 Fly Ash Fort Union Lignite 0.04% 0.22%

05-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.10% 9.68%

06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.39% 11.6%

Page 3 of 3
APPENDIX K 

pH DATA 
ID No. Sample Type Mercury Control Configuration Coal Type

Sample 

Prep

10–15-Min 

pH

10–15-Min 

pH Date 24-Hr pH

24-Hr pH 

Date

O

99-188 FGD-SDA PRB Subbituminous 12.41 5/2/2006 12.22 5/3/2006 99-188 FGD-SDA PRB Subbituminous 12.34 1/17/2002 02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.62 7/27/2004 02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.19 5/24/2006 4.76 5/25/2006 02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.91 7/27/200402-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.47 7/27/200402-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.65 7/27/200402-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.99 5/24/2006 10.95 5/25/2006 02-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.86 4/8/200402-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.47 5/24/2006 3.99 5/25/2006 02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.54 7/27/200402-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.85 5/24/2006 8.43 5/25/200602-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.94 7/27/200402-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.00 9/26/200202-070 Fly Ash Eastern Bituminous 9.98 5/24/2006 8.50 5/25/2006 02-070 Fly Ash Eastern Bituminous 10.25 9/26/200202-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.26 5/24/2006 8.63 5/25/2006 02-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.59 9/26/200202-072 Fly Ash Eastern Bituminous 10.09 5/24/2006 8.83 5/25/200602-072 Fly Ash Eastern Bituminous 10.35 9/26/2002 02-073 Fly Ash Eastern Bituminous 12.18 5/24/2006 12.44 5/25/2006 02-073 Fly Ash Eastern Bituminous 12.56 9/26/200202-074 Fly Ash Eastern Bituminous 12.00 5/30/2006 11.80 5/31/2006 02-074 Fly Ash Eastern Bituminous 12.18 9/26/200202-076 Fly Ash

South American 

Bituminous 10.38 5/30/2006 9.13 5/31/2006 

02-076 Fly Ash

South American 

Bituminous 9.93 10/19/2004

03-004 Fly Ash Eastern Bituminous 4.54 5/30/2006 7.08 5/31/2006 03-004 Fly Ash Eastern Bituminous 4.26 9/29/200303-005 Fly Ash Eastern Bituminous 4.45 5/30/2006 5.88 5/31/2006 03-005 Fly Ash Eastern Bituminous 4.26 9/29/200303-006 Fly Ash Eastern Bituminous 4.82 4/26/2006 6.78 4/27/2006 03-006 Fly Ash Eastern Bituminous 4.60 9/29/200303-007 Fly Ash Eastern Bituminous 4.38 4/26/2006 5.52 4/27/2006 03-007 Fly Ash Eastern Bituminous 4.15 9/29/200303-008 Fly Ash

South American 

Bituminous 11.72 3/14/2003

03-009 Fly Ash + Activated Carbon Pre-Primary PCD

South American 

Bituminous 11.79 3/14/2003

03-010 Fly Ash + Activated Carbon Pre-Primary PCD

South American 

Bituminous 10.34 3/14/2003

03-016 Fly Ash Fort Union Lignite 12.63 5/30/2006 12.54 5/31/2006 03-016 Fly Ash Fort Union Lignite 12.60 9/29/2003 03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.69 6/1/2006 12.61 6/2/200603-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 9/29/2003 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.58 6/1/2006 12.38 6/2/2006 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 9/29/200303-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 11.92 6/1/2006 11.86 6/2/2006 03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 11.74 10/9/2003 

Page 1 of 4
ID No. Sample Type Mercury Control Configuration Coal Type

Sample 

Prep

10–15-Min 

pH

10–15-Min 

pH Date 24-Hr pH

24-Hr pH 

Date

O

03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.31 6/1/2006 11.90 6/2/2006 03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.32 10/9/2003 03-061 Fly Ash PRB Subbituminous 11.91 6/1/2006 12.56 6/2/2006 03-061 Fly Ash PRB Subbituminous 12.02 10/10/200303-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.67 6/1/2006 12.60 6/2/2006 03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 10/10/200303-063 Fly Ash Eastern Bituminous 10.98 6/1/2006 11.00 6/2/2006 03-063 Fly Ash Eastern Bituminous 11.30 12/3/200303-065 FGD Gypsum Eastern Bituminous 8.07 5/2/2006 7.75 5/3/200603-065 FGD Gypsum Eastern Bituminous 8.59 12/3/200303-067 FGD Slurr

y Eastern Bituminous dewatered 8.95 6/21/2006 8.75 6/22/2006

03-067 FGD Slurr

y Eastern Bituminous dewatered 7.84 8/25/2005

03-067 FGD Slurr

y Eastern Bituminous 8.05 6/9/2004

03-078 Fly Ash Fort Union Lignite 11.59 12/3/200303-079 Fly Ash Fort Union Lignite 11.81 6/1/2006 11.62 6/2/2006 03-079 Fly Ash Fort Union Lignite 11.72 12/3/200303-080 Fly Ash Fort Union Lignite 11.72 6/13/2006 11.68 6/14/200603-080 Fly Ash Fort Union Lignite 11.64 12/3/2003 03-081 Fly Ash Fort Union Lignite 11.20 6/13/2006 10.50 6/14/2006 03-081 Fly Ash Fort Union Lignite 11.26 12/3/200303-082 FGD Filtercake Eastern Bituminous 8.18 5/8/2006 7.85 5/9/200603-082 FGD Filtercake Eastern Bituminous 7.47 6/9/200403-083 Fly Ash Eastern Bituminous 4.75 6/13/2006 9.00 6/14/2006 03-083 Fly Ash Eastern Bituminous 4.28 12/3/200303-084 Fixated FGD Eastern Bituminous 11.57 6/13/2006 11.03 6/14/2006 03-084 Fixated FGD Eastern Bituminous 12.52 12/3/200303-085 Fly Ash Eastern Bituminous 9.54 5/8/2006 8.79 5/9/200603-085 Fly Ash Eastern Bituminous 7.06 12/3/200303-086 FGD Filtercake Eastern Bituminous 7.81 6/13/2006 7.70 6/14/200603-086 FGD Filtercake Eastern Bituminous 7.70 6/9/200403-087 Fixated FGD Eastern Bituminous 10.87 6/13/2006 10.50 6/14/2006 03-087 Fixated FGD Eastern Bituminous 12.51 12/3/200303-088 Fly Ash Eastern Bituminous 10.72 5/2/2006 11.15 5/3/200603-088 Fly Ash Eastern Bituminous 5.02 2/12/200403-088 Fly Ash Eastern Bituminous 7.50 4/8/200403-089 FGD Gypsum Eastern Bituminous 8.13 5/2/2006 7.95 5/3/200603-089 FGD Gypsum Eastern Bituminous 8.22 4/15/200404-003 Fly Ash Eastern Bituminous 9.36 4/26/2006 8.54 4/27/2006 04-003 Fly Ash Eastern Bituminous 9.34 2/12/200404-004 Fly Ash Eastern Bituminous 9.89 4/26/2006 8.92 4/27/2006 04-004 Fly Ash Eastern Bituminous 4.47 2/12/200404-004 Fly Ash Eastern Bituminous 10.29 4/8/200404-006 Fly Ash Western Bituminous 11.56 6/13/2006 10.38 6/14/2006 04-006 Fly Ash Western Bituminous 11.52 3/4/2004 04-006 Fly Ash Western Bituminous 04-007 Fly Ash Western Bituminous 12.74 6/13/2006 12.65 6/14/2006 04-007 Fly Ash Western Bituminous 13.00 4/8/2004 04-007 Fly Ash Western Bituminous 04-029 Fly Ash PRB Subbituminous 12.56 6/15/2006 12.27 6/16/2006 04-029 Fly Ash PRB Subbituminous 12.37 4/8/2004 

Page 2 of 4
ID No. Sample Type Mercury Control Configuration Coal Type

Sample 

Prep

10–15-Min 

pH

10–15-Min 

pH Date 24-Hr pH

24-Hr pH 

Date

O

04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.56 6/15/2006 11.30 6/16/200604-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.51 4/15/2004 04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.64 6/21/2006 11.25 6/22/2006 04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.60 4/15/200404-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.54 6/15/2006 10.52 6/16/2006 04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.67 4/15/200404-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 10.70 4/15/2004 04-035 Fly Ash Fort Union Lignite 12.77 6/15/2006 12.74 6/16/2006 04-035 Fly Ash Fort Union Lignite 12.68 6/9/200404-036 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.79 6/15/2006 12.77 6/16/2006 

04-036 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.64 6/9/2004

04-042 Fly Ash Gulf Coast Lignite 11.87 6/21/2006 11.31 6/22/200604-042 Fly Ash Gulf Coast Lignite 11.77 10/19/200404-043 Fly Ash Gulf Coast Lignite 11.82 6/21/2006 11.28 6/22/200604-043 Fly Ash Gulf Coast Lignite 11.48 6/9/200404-044 Fly Ash Gulf Coast Lignite 11.76 6/21/2006 11.27 6/22/200604-044 Fly Ash Gulf Coast Lignite 11.52 10/19/200404-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.48 4/20/2006 9.20 4/21/2006 04-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.10 12/12/2005 04-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 6.40 10/19/200404-067 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.70 6/21/2006 12.60 6/22/2006

04-067 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.80 11/5/2004

04-082 FGD Gypsum Eastern Bituminous 8.19 5/8/2006 7.72 5/9/200604-082 FGD Gypsum Eastern Bituminous 8.10 2/17/200504-083 FGD Gypsum Eastern Bituminous 8.19 5/8/2006 7.80 5/9/200604-083 FGD Gypsum Eastern Bituminous 8.10 2/17/200505-001 Fly Ash Fort Union Lignite 12.50 5/2/2006 12.51 5/3/200605-001 Fly Ash Fort Union Lignite 12.84 2/22/200505-002 FGD-SDA Fort Union Lignite 12.55 5/2/2006 12.50 5/3/200605-002 FGD-SDA Fort Union Lignite 12.85 2/22/200505-003 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 12.39 5/2/2006 12.29 5/3/2006

05-003 

Fly Ash + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 12.85 3/7/2005

05-004 

FGD-SDA + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 12.51 5/2/2006 12.54 5/3/2006

05-004 

FGD-SDA + Enhancing Agent + 

Activated Carbon

Enhancing Agent on Coal, ACI 

before SDA Fort Union Lignite 13.06 3/7/2005

05-005 Fly Ash Fort Union Lignite 11.77 4/26/2006 11.57 4/27/200605-005 Fly Ash Fort Union Lignite 11.95 5/17/200505-009 FGD Gypsum Eastern Bituminous 8.68 5/8/2006 7.88 5/9/200605-009 FGD Gypsum Eastern Bituminous 8.83 8/25/200505-010 Fly Ash Eastern Bituminous 11.91 6/15/2006 11.72 6/16/200605-010 Fly Ash Eastern Bituminous 12.11 8/25/200505-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.00 4/20/2006 11.33 4/21/200605-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.05 11/3/2005

Page 3 of 4
ID No. Sample Type Mercury Control Configuration Coal Type

Sample 

Prep

10–15-Min 

pH

10–15-Min 

pH Date 24-Hr pH

24-Hr pH 

Date

O

05-017 Fly Ash + Enhancing Agent Enhancing Agent on Coal Fort Union Lignite 12.04 4/26/2006 11.77 4/27/2006

05-017 Fly Ash + Enhancing Agent Enhancing Agent on Coal Fort Union Lignite 12.19 8/25/200505-018 Fly Ash Eastern Bituminous 7.42 4/26/2006 8.49 4/27/200605-018 Fly Ash Eastern Bituminous 7.56 8/25/200505-019 FGD Filtercake Eastern Bituminous 7.90 5/8/2006 7.88 5/9/200605-019 FGD Filtercake Eastern Bituminous 8.07 11/3/200505-020 Fixated FGD Eastern Bituminous 12.10 5/8/2006 12.43 5/9/200605-020 Fixated FGD Eastern Bituminous 12.75 8/25/200505-023 Fly Ash + Activated Carbon

Post-Primary PCD: High Fly Ash 

Content Fort Union Lignite 11.35 4/20/2006 12.00 4/21/2006

05-023 Fly Ash + Activated Carbon

Post-Primary PCD: High Fly Ash 

Content Fort Union Lignite 11.65 11/3/2005

05-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.43 4/20/2006 11.41 4/21/200605-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 8.93 11/3/200505-025 Fly Ash + Activated Carbon

Post-Primary PCD: High Fly Ash 

Content Fort Union Lignite 11.53 4/20/2006 11.99 4/21/2006

05-025 Fly Ash + Activated Carbon

Post-Primary PCD: High Fly Ash 

Content Fort Union Lignite 11.67 11/3/2005

05-038 Fly Ash Fort Union Lignite 11.67 4/20/2006 11.73 4/21/200605-038 Fly Ash Fort Union Lignite 12.03 12/7/200505-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.03 4/20/2006 11.36 4/21/200605-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 6.80 12/8/2005 06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 6.69 4/4/2006 06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.20 4/20/2006 11.37 4/21/2006

Page 4 of 4
APPENDIX L 

CARBON FORMS DATA 
ID No. Sample Type Mercury Control Configuration Coal Type Dominant Carbon F

02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous

Anisotropic Coke

02-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous Isotropic Coke02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous

Anisotropic Coke

02-070 Fly Ash Eastern Bituminous Unburned Coal02-076 Fly Ash South American Bituminous

Anisotropic Coke

03-004 Fly Ash Eastern Bituminous Inertinite03-005 Fly Ash Eastern Bituminous Unburned Coal03-006 Fly Ash Eastern Bituminous Unburned Coal03-007 Fly Ash Eastern Bituminous Vitrinite03-008 Fly Ash South American Bituminous Unburned Coal03-016 Fly Ash Fort Union Lignite Vitrinite03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Inertinite03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite

Anisotropic Coke

03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Inertinite03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous

Anisotropic Coke

03-061 Fly Ash PRB Subbituminous Isotropic Coke03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Unburned Coal03-063 Fly Ash Eastern Bituminous Vitrinite03-078 Fly Ash Fort Union Lignite Vitrinite03-079 Fly Ash Fort Union Lignite

Anisotropic Coke

03-080 Fly Ash Fort Union Lignite Isotropic Coke03-083 Fly Ash Eastern Bituminous Unburned Coal

Page 1 of 1
APPENDIX M 

LEACHATE DATA 
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

99-188 FGD-SDA

PRB 

Subbituminous

18-Hour 

SGLP 3.5 0.37 116 <2 <0.01 

99-188 FGD-SDA

PRB 

Subbituminous

18-Hour 

SGLP <10 <10 105 <10 

99-188 FGD-SDA

PRB 

Subbituminous 30-Day LTL 2.6 0.58 215 <2 <0.01 

99-188 FGD-SDA

PRB 

Subbituminous 60-Day LTL 2.2 0.59 223 <2 0.043 

02-002 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

02-002 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous TCLP #1 0.01 

02-003 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

02-003 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous TCLP #1 <0.01 

02-004 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous

18-Hour 

SGLP <0.01 

02-004 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 30-Day LTL <0.01 

02-004 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 60-Day LTL <0.01 

02-004 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous TCLP #2 <0.01 

02-005 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous

18-Hour 

SGLP <0.01 

02-005 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 30-Day LTL <0.01 

02-005 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 60-Day LTL 0.01 

02-005 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous TCLP #2 <0.01 

02-006 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous

18-Hour 

SGLP 3.5 <0.2 560 <2 0.064 

Page 1 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

02-006 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous TCLP #2 <0.01 

02-007 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

02-069 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP 0.03 

02-069 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous TCLP #2 0.07 

02-070 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 0.01 

02-070 Fly Ash

Eastern 

Bituminous TCLP #2 0.03 

02-071 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP 0.01 

02-071 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous TCLP #2 <0.01 

02-072 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 0.02 

02-072 Fly Ash

Eastern 

Bituminous TCLP #2 0.02 

02-073 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 0.05 

02-073 Fly Ash

Eastern 

Bituminous TCLP #2 0.02 

02-074 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 0.01 

02-074 Fly Ash

Eastern 

Bituminous TCLP #2 0.01 

02-076 Fly Ash

South American 

Bituminous

18-Hour 

SGLP 0.016 

02-076 Fly Ash

South American 

Bituminous TCLP #2 <0.01 

03-004 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 7.7 6.27 <2 <0.01 

Page 2 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

03-004 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 9.3 1.10 9.8 <0.001 

03-004 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 10.5 1.81 11 <2 0.019 

03-004 Fly Ash

Eastern 

Bituminous 60-Day LTL 118 1.11 10.1 <2 0.012 

03-005 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 5.9 8.08 <2 <0.01 

03-005 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

03-005 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 2.9 7.36 <2 <2 0.019 

03-005 Fly Ash

Eastern 

Bituminous 60-Day LTL 6.5 7.22 <2 <2 0.239 

03-006 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 12.5 3.58 8.8 <2 <0.01 

03-006 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 10.0 3.00 7.4 <0.001 

03-006 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 19.2 4.31 <2 <0.01 

03-006 Fly Ash

Eastern 

Bituminous 60-Day LTL 110 1.37 7.5 <2 0.06 

03-007 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 20.0 7.83 <2 <0.01 

03-007 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 16.2 7.58 2.0 <2 <0.01 

03-007 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 15.0 7.30 1.4 <0.001 

03-007 Fly Ash

Eastern 

Bituminous 60-Day LTL 10.6 6.70 <2 <2 <0.01 

03-008 Fly Ash

South American 

Bituminous

18-Hour 

SGLP <0.01 

03-008 Fly Ash

South American 

Bituminous TCLP #2 0.034 

Page 3 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

03-009 

Fly Ash + Activated 

Carbon Pre-Primary PCD

South American 

Bituminous

18-Hour 

SGLP <0.01 

03-009 

Fly Ash + Activated 

Carbon Pre-Primary PCD

South American 

Bituminous TCLP #2 <0.01 

03-010 

Fly Ash + Activated 

Carbon Pre-Primary PCD

South American 

Bituminous

18-Hour 

SGLP <0.01 

03-010 

Fly Ash + Activated 

Carbon Pre-Primary PCD

South American 

Bituminous TCLP #2 <0.01 

03-060 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous

18-Hour 

SGLP 2.7 <0.2 <50 <2 <0.01 

03-060 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous

18-Hour 

SGLP <2 0.22 54.1 <2 0.025 

03-060 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 30-Day LTL <2 <0.2 6.3 3.0 <0.01 

03-060 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 60-Day LTL <0.01 

03-060 

Fly Ash + Activated 

Carbon Pre-Primary PCD

PRB 

Subbituminous 60-Day LTL <2 <0.2 10.7 2.4 0.068 

03-061 Fly Ash

PRB 

Subbituminous

18-Hour 

SGLP 2.0 <2 <2 <0.01 

03-061 Fly Ash

PRB 

Subbituminous

18-Hour 

SGLP <2 <0.2 15.5 <2 0.018 

03-061 Fly Ash

PRB 

Subbituminous 30-Day LTL <2 <0.2 3.0 3.6 <0.01 

03-061 Fly Ash

PRB 

Subbituminous 60-Day LTL <2 <0.2 3.2 8.5 0.325 

03-062 

Fly Ash + Activated 

Carbon Pre-Primary PCD Fort Union Lignite

18-Hour 

SGLP 6.6 0.34 80.0 <2 <0.01 

03-062 

Fly Ash + Activated 

Carbon Pre-Primary PCD Fort Union Lignite

18-Hour 

SGLP 6.0 0.45 103 <2 <0.01 

03-062 

Fly Ash + Activated 

Carbon Pre-Primary PCD Fort Union Lignite

18-Hour 

SGLP <4 <0.3 99.0 <0.001 

03-062 

Fly Ash + Activated 

Carbon Pre-Primary PCD Fort Union Lignite 30-Day LTL <2 <0.2 3.6 <2 <0.01 

Page 4 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

03-062 

Fly Ash + Activated 

Carbon Pre-Primary PCD Fort Union Lignite 60-Day LTL 5.2 <0.2 5.2 <2 <0.01 

03-063 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 67.8 <0.2 <2 <0.01 

03-063 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 52.0 <0.3 38.8 <0.001 

03-063 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 60.2 0.57 43.5 <2 <0.01 

03-063 Fly Ash

Eastern 

Bituminous 30-Day LTL 37.7 0.64 38.6 <2 <0.01 

03-063 Fly Ash

Eastern 

Bituminous 60-Day LTL 36.1 0.61 38.8 <2 0.038 

03-065 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <2 <0.2 <2 <2 <0.01 

03-065 FGD Gypsum

Eastern 

Bituminous 60-Day LTL <2 <0.2 <2 <2 <0.01 

03-067 FGD Slurry

Eastern 

Bituminous

18-Hour 

SGLP <4 <0.3 <1 <0.001 0.047 

03-078 Fly Ash Fort Union Lignite

18-Hour 

SGLP 95.1 0.43 150 <2 <0.01 

03-078 Fly Ash Fort Union Lignite

18-Hour 

SGLP 90.5 4.47 166 <2 <0.01 

03-079 Fly Ash Fort Union Lignite

18-Hour 

SGLP 75.7 0.37 150 <2 <0.01 

03-079 Fly Ash Fort Union Lignite

18-Hour 

SGLP 74.8 3.71 174 <2 <0.01 

03-079 Fly Ash Fort Union Lignite 30-Day LTL 45.3 4.23 265 <2 <0.01 03-079 Fly Ash Fort Union Lignite 60-Day LTL 59.8 3.96 250 <2 0.049 03-079 Fly Ash Fort Union Lignite 60-Day LTL 49.3 4.40 277 <2 <0.01 03-079 Fly Ash Fort Union Lignite 60-Day LTL <0.01 03-080 Fly Ash Fort Union Lignite

18-Hour 

SGLP 44.6 1.57 90.0 <2 0.011 

03-080 Fly Ash Fort Union Lignite 30-Day LTL 35.2 1.97 134 <2 0.113 03-080 Fly Ash Fort Union Lignite 60-Day LTL 29.2 2.06 110 <2 0.041 03-080 Fly Ash Fort Union Lignite 60-Day LTL 28.7 2.14 135 <2 <0.01 

Page 5 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

03-081 Fly Ash Fort Union Lignite

18-Hour 

SGLP 140 3.75 120 <2 0.083 

03-081 Fly Ash Fort Union Lignite 30-Day LTL 232 6.02 264 <2 0.013 03-081 Fly Ash Fort Union Lignite 60-Day LTL 226 5.38 230 <2 0.019 03-081 Fly Ash Fort Union Lignite 60-Day LTL 0.017 03-081 Fly Ash Fort Union Lignite 60-Day LTL 223 5.60 273 <2 0.124 03-082 FGD Filtercake

Eastern 

Bituminous

18-Hour 

SGLP 3.7 <0.2 <2 <2 0.404 

03-082 FGD Filtercake

Eastern 

Bituminous 30-Day LTL <0.01 

03-082 FGD Filtercake

Eastern 

Bituminous 30-Day LTL 3.5 0.83 <2 <2 <0.01 

03-082 FGD Filtercake

Eastern 

Bituminous 60-Day LTL <2 0.47 <2 <2 <0.01 

03-083 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 48.0 <0.3 9.1 <0.001 

03-083 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 54.3 2.92 10.7 <2 <0.01 

03-083 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 97.3 <0.2 <2 <0.01 

03-084 Fixated FGD

Eastern 

Bituminous

18-Hour 

SGLP 4.9 0.44 4.7 14.3 0.289 

03-084 Fixated FGD

Eastern 

Bituminous 30-Day LTL <0.01 

03-084 Fixated FGD

Eastern 

Bituminous 30-Day LTL 5.2 0.66 3.1 <2 <0.01 

03-084 Fixated FGD

Eastern 

Bituminous 60-Day LTL <2 0.48 2.4 <2 <0.01 

03-084 Fixated FGD

Eastern 

Bituminous 60-Day LTL <2 0.50 2.5 <2 <0.01 

03-085 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

03-085 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 250 2.57 21.3 <2 <0.01 

Page 6 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

03-085 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 250 <0.3 19.5 <0.001 

03-085 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 266 0.28 <2 <0.01 

03-087 Fixated FGD

Eastern 

Bituminous

18-Hour 

SGLP 7.0 0.43 3.0 6.6 0.237 

03-087 Fixated FGD

Eastern 

Bituminous 30-Day LTL 24.0 0.30 2.2 <2 <0.01 

03-087 Fixated FGD

Eastern 

Bituminous 60-Day LTL 19.1 0.37 3.3 <2 <0.01 

03-088 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 18.4 4.93 110 <2 0.029 

03-088 Fly Ash

Eastern 

Bituminous 30-Day LTL 23.0 7.64 160 <2 <0.01 

03-088 Fly Ash

Eastern 

Bituminous 60-Day LTL 23.4 8.30 180 <2 <0.01 

03-089 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <2 0.46 <2 <2 <0.01 

03-089 FGD Gypsum

Eastern 

Bituminous 60-Day LTL <2 <0.2 <2 <2 <0.01 

04-003 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 188 0.56 48.8 <2 <0.01 

04-003 Fly Ash

Eastern 

Bituminous 30-Day LTL 305 0.88 69.3 <2 0.104 

04-003 Fly Ash

Eastern 

Bituminous 60-Day LTL 282 0.71 70.6 <2 <0.01 

04-003 Fly Ash

Eastern 

Bituminous 60-Day LTL 336 0.77 70.0 <2 <0.01 

04-004 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 136 0.70 70.0 <2 <0.01 

04-004 Fly Ash

Eastern 

Bituminous 30-Day LTL 135 1.02 98.1 <2 <0.01 

04-004 Fly Ash

Eastern 

Bituminous 60-Day LTL 140 0.84 100 <2 0.077 

Page 7 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

04-006 Fly Ash

Western 

Bituminous

18-Hour 

SGLP <0.01 

04-006 Fly Ash

Western 

Bituminous

18-Hour 

SGLP 12.3 0.28 34.6 <2 <0.01 

04-006 Fly Ash

Western 

Bituminous 30-Day LTL 3.4 0.36 49.2 <2 0.076 

04-006 Fly Ash

Western 

Bituminous 60-Day LTL 7.3 0.33 52.8 <2 0.087 

04-007 Fly Ash

Western 

Bituminous

18-Hour 

SGLP 10.7 <2 120 <2 0.021 

04-007 Fly Ash

Western 

Bituminous 30-Day LTL <2 <0.2 7.3 2.2 0.035 

04-007 Fly Ash

Western 

Bituminous 60-Day LTL <2 <0.2 6.7 <2 <0.01 

04-029 Fly Ash

PRB 

Subbituminous

18-Hour 

SGLP <2 <0.2 24.1 <2 0.023 

04-029 Fly Ash

PRB 

Subbituminous 30-Day LTL <2 <0.2 5.1 <2 <0.01 

04-029 Fly Ash

PRB 

Subbituminous 60-Day LTL <2 <0.2 2.3 <2 <0.01 

04-030 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 26.9 1.40 399 <2 <0.01 

04-030 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 8.1 1.86 640 <2 <0.01 

04-030 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 10.6 2.35 670 <2 <0.01 

04-031 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 23.2 1.49 410 <2 0.012 

04-031 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 9.6 1.95 650 <2 <0.01 

04-031 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 11.5 2.34 680 <2 0.028 

04-032 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 28.0 1.24 333 <2 <0.01 

Page 8 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

04-033 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 31.1 1.32 351 <2 <0.01 

04-033 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 10.1 1.99 580 <2 <0.01 

04-033 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 10.4 2.46 620 <2 <0.01 

04-035 Fly Ash Fort Union Lignite

18-Hour 

SGLP <2 <0.2 55.8 <2 0.081 

04-035 Fly Ash Fort Union Lignite 30-Day LTL <2 <0.2 <2 <2 0.02 04-035 Fly Ash Fort Union Lignite 60-Day LTL <2 <0.2 2.1 <2 <0.01 04-036 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI PrePrimary PCD Fort Union Lignite 18-Hour SGLP <2 0.27 67.6 3.0 0.016 

04-036 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI PrePrimary PCD Fort Union Lignite 18-Hour SGLP <0.01 

04-036 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI PrePrimary PCD Fort Union Lignite 30-Day LTL <2 <0.2 <2 <2 <0.01 

04-036 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI PrePrimary PCD Fort Union Lignite 60-Day LTL <2 <0.2 2.1 <2 <0.01 

04-054 

Fly Ash + Activated 

Carbon Post-Primary PCD

Eastern 

Bituminous

18-Hour 

SGLP 842 1.87 17.3 <2 <0.01 

04-067 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI PrePrimary PCD Fort Union Lignite 18-Hour SGLP 15.2 0.39 <2 2.2 <0.01 

04-082 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <2 0.33 <2 <2 <0.01 

04-082 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <0.01 

04-083 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <2 0.25 <2 <2 <0.01 

05-001 Fly Ash Fort Union Lignite

18-Hour 

SGLP 3.0 0.24 45.3 <2 <0.01 

Page 9 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

05-001 Fly Ash Fort Union Lignite 30-Day LTL <4 <0.3 153 <0.001 <0.01 05-001 Fly Ash Fort Union Lignite 30-Day LTL 2.1 0.26 132 <2 0.016 05-001 Fly Ash Fort Union Lignite 60-Day LTL 2.5 0.22 152 <2 0.011 05-002 FGD-SDA Fort Union Lignite

18-Hour 

SGLP 2.1 0.22 34.6 <2 <0.01 

05-002 FGD-SDA Fort Union Lignite 30-Day LTL <4 <0.3 126 <0.001 <0.01 05-002 FGD-SDA Fort Union Lignite 30-Day LTL 3.3 <0.2 113 <2 0.095 05-002 FGD-SDA Fort Union Lignite 60-Day LTL 2.3 0.20 132 <2 0.013 05-003 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite

18-Hour 

SGLP 7.2 0.30 49.9 <2 <0.01 

05-003 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 30-Day LTL <4 <0.3 133 <0.001 <0.05 

05-003 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 30-Day LTL 6.4 <0.2 123 <2 0.061 

05-003 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 60-Day LTL 7.5 <0.2 133 <2 0.016 

05-003 

Fly Ash + Enhancing 

Agent + Activated 

Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 60-Day LTL 6.9 <0.2 134 <2 0.013 

05-004 

FGD-SDA + 

Enhancing Agent + 

Activated Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite

18-Hour 

SGLP 4.3 0.20 21.8 <2 <0.01 

05-004 

FGD-SDA + 

Enhancing Agent + 

Activated Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 30-Day LTL <4 <0.3 78.0 <0.001 <0.02 

05-004 

FGD-SDA + 

Enhancing Agent + 

Activated Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 30-Day LTL 3.6 <0.2 67.7 <2 <0.01 

05-004 

FGD-SDA + 

Enhancing Agent + 

Activated Carbon

Enhancing Agent 

on Coal, ACI 

before SDA Fort Union Lignite 60-Day LTL 3.8 <0.2 87.7 <2 0.012 

Page 10 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

05-005 Fly Ash Fort Union Lignite

18-Hour 

SGLP 134 2.79 137 <2 <0.01 

05-005 Fly Ash Fort Union Lignite

18-Hour 

SGLP <0.01 

05-005 Fly Ash Fort Union Lignite 30-Day LTL <0.01 05-005 Fly Ash Fort Union Lignite 30-Day LTL 101 2.48 179 <2 <0.01 05-005 Fly Ash Fort Union Lignite 60-Day LTL 140 <0.3 166 <0.001 05-005 Fly Ash Fort Union Lignite 60-Day LTL 160 2.65 183 <2 <0.01 05-005 Fly Ash Fort Union Lignite 60-Day LTL <0.01 05-005 Fly Ash Fort Union Lignite 60-Day LTL <0.01 05-009 FGD Gypsum

Eastern 

Bituminous

18-Hour 

SGLP <4 <0.3 <1 <0.001 <0.01 

05-010 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 41.0 <0.3 19.4 <0.001 <0.01 

05-013 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 30.4 1.29 112 <2 <0.01 

05-013 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 30.4 1.08 159 <2 <0.01 

05-013 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 27.3 1.14 156 <2 <0.01 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite

18-Hour 

SGLP <0.01 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 30-Day LTL <0.01 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 30-Day LTL 46.3 2.40 203 <2 <0.01 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 60-Day LTL <0.01 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 60-Day LTL 73.0 <0.3 182 <0.001 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 60-Day LTL 95.3 2.55 206 <2 0.02 

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 60-Day LTL 95.9 2.68 211 <2 0.012 

Page 11 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

05-017 

Fly Ash + Enhancing 

Agent

Enhancing Agent 

on Coal Fort Union Lignite 60-Day LTL <0.01 

05-018 Fly Ash

Eastern 

Bituminous

18-Hour 

SGLP 150 <0.3 11.1 <0.001 0.022 

05-019 FGD Filtercake

Eastern 

Bituminous

18-Hour 

SGLP <4 <0.3 <1 <0.001 0.476 

05-023 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite

18-Hour 

SGLP 14.5 1.01 168 <2 <0.01 

05-023 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite 30-Day LTL 8.1 0.75 134 <2 <0.01 

05-023 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite 60-Day LTL 9.1 0.72 138 <2 <0.01 

05-024 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 24.6 1.50 141 <2 <0.01 

05-024 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 17.9 1.13 173 <2 <0.01 

05-024 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 14.0 1.16 167 <2 <0.01 

05-025 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite

18-Hour 

SGLP 16.3 1.49 153 <2 <0.01 

05-025 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite 30-Day LTL 9.9 1.06 147 <2 <0.01 

05-025 

Fly Ash + Activated 

Carbon

Post-Primary 

PCD: High Fly Ash 

Content Fort Union Lignite 60-Day LTL 11.7 0.90 133 <2 <0.01 

05-038 Fly Ash Fort Union Lignite

18-Hour 

SGLP 8.1 1.10 169 <2 <0.01 

05-038 Fly Ash Fort Union Lignite 30-Day LTL 2.4 0.58 92.0 <2 <0.01 05-038 Fly Ash Fort Union Lignite 60-Day LTL <2 0.67 88.6 <2 <0.01 

Page 12 of 13
ID No. Sample Type

Hg Control 

Configuration Coal Type

Leachate 

Test

As 

(μg/L)

Cd 

(μg/L)

Cr 

(μg/L)

Pb 

(μg/L)

Hg 

(μg/L)

(

05-040 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 20.9 1.35 112 <2 <0.01 

05-040 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 17.0 0.96 152 <2 <0.01 

05-040 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 15.6 1.08 155 <2 <0.01 

06-001 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 20.2 0.99 119 <2 <0.01 

06-001 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite

18-Hour 

SGLP 21.3 1.01 120 <2 <0.01 

06-001 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 30-Day LTL 18.6 0.85 166 <2 <0.01 

06-001 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 17.5 0.89 160 <2 <0.01 

06-001 

Fly Ash + Activated 

Carbon Post-Primary PCD Fort Union Lignite 60-Day LTL 17.7 0.85 157 <2 <0.01 

Page 13 of 13
APPENDIX N 

MERCURY AND AIR TOXIC ELEMENT 

LEACHING FROM COAL COMBUSTION 

BY-PRODUCTS 
MERCURY AND AIR TOXIC ELEMENT 

LEACHING FROM COAL COMBUSTION 

BY-PRODUCTS 

Topical Report 

Ms. Lynn Brickett 

U.S. Department of Energy 

National Energy Technology Laboratory 

626 Cochrans Mill Road 

PO Box 10940, MS 922-273C 

Pittsburgh, PA 15236-0940 

Cooperative Agreement No. DE-FC26-03NT41727 

 

Prepared by: 

Debra F. Pflughoeft-Hassett 

David J. Hassett 

Tera D. Buckley 

Loreal V. Heebink 

Erick J. Zacher 

Energy & Environmental Research Center 

University of North Dakota 

PO Box 9018 

Grand Forks, ND 58202-9018 

2005-EERC-08-08 August 2005 
EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental 

Research Center (EERC), an agency of the University of North Dakota, as an account of work 

sponsored by the U.S. Department of Energy (DOE), the Center for Air Toxic Metals®, Cynergy, 

the Utility Solid Waste Activities Group, the North Dakota Industrial Commission, and Great 

River Energy. Because of the research nature of the work performed, neither the EERC nor any 

of its employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement 

or recommendation by the EERC. 

DOE DISCLAIMER

 This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 

NDIC DISCLAIMER 

 This report was prepared by the Energy & Environmental Research Center (EERC) 

pursuant to an agreement partially funded by the Industrial Commission of North Dakota, and 

neither the EERC nor any of its subcontractors nor the North Dakota Industrial Commission nor 

any person acting on behalf of either: 

(A) Makes any warranty or representation, express or implied, with respect to the 

accuracy, completeness, or usefulness of the information contained in this report, or 

that the use of any information, apparatus, method, or process disclosed in this report 

may not infringe privately owned rights; or 

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the 

use of, any information, apparatus, method, or process disclosed in this report. 

 Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 
recommendation, or favoring by the North Dakota Industrial Commission. The views and 

opinions of authors expressed herein do not necessarily state or reflect those of the North Dakota 

Industrial Commission 

ACKNOWLEDGMENT

 This report was prepared with the support of DOE National Energy Technology 

Laboratory Cooperative Agreement No. DE-FC21-93MC30098. However, any opinions, 

findings, conclusions, or recommendations expressed herein are those of the authors(s) and do 

not necessarily reflect the views of DOE. 
i 

TABLE OF CONTENTS 

LIST OF FIGURES ........................................................................................................................ ii 

LIST OF TABLES.........................................................................................................................iii 

EXECUTIVE SUMMARY ........................................................................................................... iv 

INTRODUCTION .......................................................................................................................... 1 

BACKGROUND ............................................................................................................................ 2 

OBJECTIVES................................................................................................................................. 2 

METHODS ..................................................................................................................................... 3 

LEACHING RESULTS AND DISCUSSION................................................................................ 3 

 Mercury Leaching Results .................................................................................................... 5 

 Other Air Toxic Element Leaching Results .......................................................................... 9 

 Arsenic......................................................................................................................... 9 

 Cadmium.................................................................................................................... 11 

 Chromium.................................................................................................................. 11 

 Lead ........................................................................................................................... 14 

 Nickel......................................................................................................................... 14 

 Selenium .................................................................................................................... 18

SUMMARY.................................................................................................................................. 20 

REFERENCES ............................................................................................................................. 20 

Hg/ATE Project Sample Set and Analysis Status..........................................................Appendix A 

Tables.............................................................................................................................Appendix B 

Figures............................................................................................................................Appendix C 
ii 

LIST OF FIGURES 

1 Total mercury vs. short- and long-term leachable mercury: all fly ash – without 

mercury control and fly ash – with mercury control samples. The x-axis is reduced 

from 120 μg/g ......................................................................................................................... 5 

2 Total mercury vs. short- and long-term leachable mercury: all available paired fly ash 

samples. One paired sample set has two fly ash – with mercury control samples ................. 6 

3 Total mercury vs. SGLP leachable mercury: all available paired fly ash samples. One 

paired sample set has two fly ash – with mercury control samples........................................ 7 

4 Total mercury vs. SGLP and TCLP leachable mercury: all available paired fly ash 

samples. One paired sample set has two fly Ash – with mercury control samples ................ 7 

5 Total mercury vs. short- and long-term leachable mercury: all FGD material samples......... 8 

6 Total arsenic vs. short- and long-term leachable arsenic: all fly ash – without mercury 

control and fly ash – with mercury control samples............................................................... 9 

7 Total arsenic vs. SGLP leachable arsenic: all available paired fly ash samples................... 10 

8 Total arsenic vs. short- and long-term leachable arsenic: all FGD material samples. One 

sample had a total arsenic LLQ higher than the reported value of another sample.............. 10 

9 Total cadmium vs. short- and long-term leachable cadmium: all fly ash – without 

mercury control and fly ash – with mercury control samples............................................... 11 

10 Total cadmium vs. SGLP leachable cadmium: all available paired fly ash samples............ 12 

11 Total cadmium vs. short- and long-term leachable cadmium: all FGD material samples.... 12 

12 Total chromium vs. short- and long-term leachable chromium: all fly ash – without 

mercury control and fly ash – with mercury control samples. Several samples had a 

leachable chromium LLQ higher than the reported values of other samples ....................... 13 

13 Total chromium vs. SGLP leachable chromium: all available paired fly ash samples. 

One paired sample set had a leachable chromium LLQ higher than the reported values 

of other samples .................................................................................................................... 13 

14 Total chromium vs. short- and long-term leachable chromium: all FGD material 

samples.................................................................................................................................. 14 

15 Total lead vs. short- and long-term leachable lead: all fly ash – without mercury control 

and fly ash – with mercury control samples ......................................................................... 15 

Continued. . . 
iii 

LIST OF FIGURES (Continued) 

16 Total lead vs. SGLP leachable lead: all available paired fly ash samples ............................ 15 

17 Total lead vs. short- and long-term leachable lead: all FGD material samples .................... 16 

18 Total nickel vs. short- and long-term leachable nickel: all fly ash – without mercury 

control and fly ash – with mercury control samples. Several samples had a leachable 

nickel LLQ higher than the reported values of other samples. The x-axis is reduced 

from 300 μg/g ....................................................................................................................... 16 

19 Total nickel vs. SGLP leachable nickel: all available paired fly ash samples. One paired 

sample set had a leachable nickel LLQ higher than the reported values of other samples... 17 

20 Total nickel vs. short- and long-term leachable nickel: all FGD material samples.............. 17 

21 Total selenium vs. short- and long-term leachable selenium: all fly ash – without mercury 

control and fly ash – with mercury control samples. The x-axis is reduced from 

450 μg/g. The y-axis is reduced from 9000 μg/g.................................................................. 18 

22 Total selenium vs. SGLP leachable selenium: all available paired fly ash samples............. 19 

23 Total selenium vs. short- and long-term leachable selenium: all FGD material samples..... 19 

LIST OF TABLES 

1 Fly Ash Sample Types and Descriptions................................................................................ 4 

2 FGD Material Types and Descriptions ................................................................................... 4 
iv 

MERCURY AND AIR TOXIC ELEMENT LEACHING FROM COAL COMBUSTION 

BY-PRODUCTS 

EXECUTIVE SUMMARY 

 Under this 3-year project, funded by the U.S. Department of Energy and industry, the 

Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other 

air toxic elements on the management of coal combustion by-products (CCBs). The EERC is 

measuring the release of mercury and other air toxic elements from fly ash and flue gas 

desulfurization (FGD) material under different controlled laboratory conditions. One key release 

mechanism is being investigated in the laboratory is that of mercury and other air toxic element 

releases by direct leaching. The goal of the leaching task was to develop a broad set of mercury 

and air toxic element leaching data on CCBs in order to determine the leachability of these 

elements from CCBs generated at existing systems and mercury emission control test systems.

Tests of direct leachability have long been used to assess the environmental performance of 

CCBs, and the EERC has elected to apply short- and long-term batch leaching procedures to 

samples of fly ash and FGD material that have been assembled for this project. The project 

sample set includes samples of fly ash and FGD material that were obtained from full-scale coalfired power plants operating under typical conditions and with no mercury control technologies 

being used. The sample set also includes fly ash samples and one FGD sample that were 

collected at pilot- and full-scale facilities while mercury control technologies were being tested. 

 Leaching data were assembled and presented in two formats: 1) a comparison of total 

elemental concentration with leachate concentrations for all samples without and with mercury 

controls for fly ash and separately for FGD materials and 2) a comparison of “paired” fly ash 

samples with a true baseline fly ash sample without mercury control and a test fly ash sample 

with mercury control. Key conclusions drawn from the mercury leaching data are as follows: 

• Total mercury content of samples generated both without and with mercury emission 

controls present and mercury leachate concentrations did not correlate. 

• Leachate mercury concentrations were independent of short-term leaching procedures 

used. 

• Leachate mercury concentrations have been found to be extremely low regardless of 

the total mercury content of the sample.

• Total mercury content of paired test fly ash samples with mercury control was 

consistently higher than the paired baseline fly ash sample without mercury control.

 Leaching data for other air toxic elements did not indicate any consistent increase in total 

elemental content where mercury control was in place. Leaching profiles tended to be sampledependent. Additional leaching work is planned to increase the data set for the other air toxic 

elements and specifically for FGD materials. 
1 

MERCURY AND AIR TOXIC ELEMENT LEACHING FROM COAL COMBUSTION 

BY-PRODUCTS 

INTRODUCTION 

 The stability of mercury associated with coal combustion by-products (CCBs) has become 

a prominent question as the coal-fired utility industry works to develop and test mercury 

emission controls that may consequently increase the mercury associated with CCBs. The 

reasons for evaluating the release of mercury from CCBs are 1) to determine if mercury captured 

on CCBs is stable or if it will be released, thus negating the purpose of the removal of the 

mercury from the emissions, and 2) to aid utilities in determining and understanding potential 

changes in CCBs associated with mercury control and associated CCB management. 

 Under this 3-year project, funded by the U.S. Department of Energy (DOE) and industry, 

the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and 

other air toxic elements on the management of CCBs. The EERC is measuring the release of 

mercury and other air toxic elements under different controlled laboratory conditions and 

investigating the release of these same air toxic elements in select field settings. Results will be 

used to determine if mercury release from CCBs, both as currently produced and as produced 

with mercury and other emission controls in place, will potentially impact CCB management 

practices. 

 Laboratory tasks were designed to address three primary potential release mechanisms for 

mercury over the life cycle of CCBs in a variety of management scenarios. These release 

mechanisms are: 

1. Direct leachability of air toxic constituents from CCBs. 

2. Vapor release of mercury from CCBs at ambient and elevated temperatures. 

3. Biologically mediated leachability and vapor release of mercury and other air toxic 

elements from CCBs. 

 This report focuses on the results generated from the assessment of the direct leachability 

of mercury and other air toxic elements from CCBs. Tests of direct leachability have long been 

used to assess the environmental performance of CCBs as well as other materials, by-products, 

and wastes for both organic and inorganic constituents. In this project, inorganic constituents, 

and especially air toxic elements were the focus. The air toxic elements included in the 

evaluations were mercury, arsenic, cadmium, chromium, lead, nickel, and selenium. All of these 

elements have been found to be present on CCBs and to exhibit leachability under various 

conditions. This report is a preliminary summary of leaching results for the overall project 

entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization.” 
2 

BACKGROUND 

 Leaching tests have been applied to CCBs as the primary means of assessing the potential 

for constituents present in CCBs to be released to the environment when these materials are 

placed in the environment. Over the last nearly 28 years, researchers at the EERC have leached a 

very large number of various CCBs. Many groups have worked to develop appropriate leaching 

tests for a variety of materials including CCBs, understand leaching mechanisms of various 

materials, and assemble leachate data sets. Kim (1) and Sorini (2) published summaries of 

available leaching methods, and Kim (3) published results of extensive leaching studies of 

CCBs. Even though a broad variety of leaching tests of varying types (batch, serial batch, flowaround, flow-through, etc. [1, 2]) are published, the EERC has concluded that an appropriate 

leaching test for the assessment of the potential for environmental impact of CCBs must meet the 

following criteria if it is to stand up to legal and scientific scrutiny: 

• The test must take into account any reactivity or unusual properties of the material 

being leached. 

• The test must as closely as possible utilize a leaching solution that mimics the leaching 

solution most likely to contact the material in its use or disposal setting. 

• If the ash is reactive with water, the test must take this into account by allowing the 

hydration reactions to occur during the course of the leaching test. This necessitates the 

use of long-term leaching (LTL). 

 The EERC developed a test that meets these criteria (4). The test is referred to as the 

synthetic groundwater leaching procedure (SGLP) and generally includes an 18-hour batch 

leaching test and two longer-term leaching tests. 30- and 60-day leaching times are 

recommended for the long-term tests. 

OBJECTIVES 

 The goal of the leaching task was to develop a broad set of mercury and air toxic element 

leaching data on CCBs in order to determine the leachability of these elements from CCBs 

generated at existing systems and mercury emission control test systems. Supporting objectives 

were to: 

• Select and apply one or more appropriate laboratory leaching methods to evaluate the 

potential for release of mercury and other air toxic elements from CCBs under 

conditions that are relevant to management options applied to CCBs. 

• Develop leaching data on “paired” samples from systems where baseline and test 

samples were available. 

• Draw conclusions about the mobility of these elements, especially mercury, that may 

impact choices for CCB management options. 
3 

METHODS 

A report entitled “Laboratory Methods for the Evaluation of Potential Release of Mercury 

from Coal Utilization By-Products” was published in April 2005 under separate cover for this 

project. A discussion of methods available and the justification for method selection is included 

in detail in that report and is not replicated in this report. The leaching tests performed on the 

samples in this project were the toxicity characteristic leaching procedure (TCLP) (5), SGLP, 

and LTL with 30- and 60-day equilibration periods. 

 Under this project, the EERC is participating in an interlaboratory comparative study of 

leaching procedures and has provided a sample of regional fly ash for inclusion in the 

comparative study. Participants in that study are the DOE National Energy Technology 

Laboratory (NETL), the EERC, the University of the Western Cape Department of Chemistry, 

the Virginia Tech Department of Crop and Soil Environmental Sciences, and the West Virginia 

Water Research Institute National Mine Land Reclamation Center (WVWRI). The methods 

being compared are those developed at NETL, WVWRI, the EERC, and the 3-tier procedure 

published by Kosson and others (6). The EERC results of this interlaboratory study were not yet 

available at the writing of this report but will be included in future project reports. 

LEACHING RESULTS AND DISCUSSION 

 Sample descriptions for samples included in this study are shown in Appendix A. All 

leaching data are included in tabular form in Appendix B. As can be noted in Appendix B, not all 

leaching procedures were applied to all samples. Where TCLP was included as one of the 

procedures applied, it was generally included because of specific requests from the sample 

submitter. SGLP was generally applied to all submitted samples, and as noted in the report 

entitled “Laboratory Methods for the Evaluation of Potential Release of Mercury from Coal 

Utilization Byproducts,” SGLP applied using distilled deionized water is equivalent to ASTM 

International D3987 Standard Test Method for Shake Extraction of Solid Waste with Water (7). 

For samples with a pH >10, the LTL procedure was also applied in order to assess the impact of 

reactivity of the material on the leaching profile of the sample. 

 Fly ash samples evaluated in this study for leachability of mercury and other air toxic 

elements were from several sources and are delineated in the graphics in this report as noted in 

Table 1. 

 Similarly, a variety of flue gas desulfurization (FGD) material samples were evaluated for 

leachability of mercury and other air toxic elements. Table 2 details the types and descriptions 

used for the FGD materials included in the study. 
4 

 Table 1. Fly Ash Sample Types and Descriptions

Types of Fly Ash Sample Description Used in Report Figures 

Currently generated fly ash from existing 

coal-fired system 

Fly ash – without mercury control 

Fly ash collected from coal-fired system 

with mercury emission control installed 

(usually as a demonstration) 

Fly ash – with mercury control* 

Fly ash collected at true baseline conditions 

in a system preparing to run a mercury 

emission control technology test 

Baseline fly ash (a subset of “Fly ash – 

without mercury control”) 

Fly ash collected during a mercury 

emission control technology test where a 

baseline fly ash sample was also collected 

Paired fly ash – with mercury control* (a 

subset of “Fly ash –with mercury control”) 

* Note: “with mercury control” indicates the presence of activated carbon. 

 Table 2. FGD Material Types and Descriptions 

Types of FGD Materials Sample Description Used in Report Figures 

Currently generated FGD material from 

existing coal-fired system 

FGD material – without mercury control 

FGD material collected from system with 

mercury emission control installed (usually 

as a demonstration) 

FGD material –with mercury control 

FGD material collected at true baseline 

conditions in a system preparing to run a 

mercury emission control technology test 

Baseline FGD material (a subset of “FGD 

material – without mercury control”) 

FGD material collected during a mercury 

emission control technology test where a 

baseline FGD material was also collected 

Paired FGD material –with mercury control 

(a subset of “FGD material – with mercury 

control”) 

 In the text of this report, multiple figures are included for mercury and each of the air toxic 

elements of interest, as follows: 

1. A figure comparing the total elemental concentration to all short- and long-term 

leachate concentrations generated in the project for all samples of fly ash without and 

with mercury control. Blue is used to represent concentrations of samples without

mercury control and red represents samples with mercury control. 

2. A figure showing the SGLP leaching results for the paired fly ash samples, where 

paired samples are represented with one color with open points for fly ash without

mercury control and solid points for the paired fly ash with mercury control. 

3. A figure showing all leachate results for all FGD materials evaluated including the only 

FGD material paired sample set, which are noted in each of these figures. Blue points 

represent results of samples without mercury control and a red point is used to 
5 

represent the one sample generated with mercury control. In addition, samples of FGD 

gypsum collected at a single bituminous-fired facility with selective catalytic reduction 

(SCR) on and off are called out; however, these samples are not “paired” samples 

because they were collected several months apart. 

 Appendix C includes figures showing the short- and long-term leaching data for individual 

paired fly ash samples. The SGLP-only graphs were used in the text to allow ease of viewing the 

data, and the graphs of individual paired fly ash sample sets provide more detail and allow 

comparison of the short- and long-term leaching results. 

 Several samples had total elemental or leachate concentrations below the lower limit of 

quantitation (LLQ). The LLQs were variable throughout the project, with some reported values 

below the LLQ of other samples. Therefore, these values are represented as one-half the LLQ 

graphically, and a red dashed line represents the highest LLQ. 

 Mercury Leaching Results 

 Mercury was the element of greatest interest for this project, and significant data were 

produced through Year 2 of the project on the leaching profiles of mercury associated with fly 

ash. Additional figures are presented in the text for mercury leaching results. Figure 1 shows all 

short- and long-term leaching data for mercury for fly ash samples both without and with

mercury control. 

Figure 1. Total mercury vs. short- and long-term leachable mercury: all fly ash – without

mercury control and fly ash – with mercury control samples. The x-axis is reduced from 

120 μg/g. 
6 

 Figure 2 shows all short- and long-term mercury leaching data for baseline fly ash without

mercury control and the paired fly ash with mercury control in addition to Figure 3, which shows 

only the SGLP mercury leaching data for this same sample set. In Figures 2 and 3, the baseline 

fly ash results are noted as open points and the paired fly ash with mercury control is noted as 

solid points. Paired samples are denoted by the same color points. 

 A comparison of short-term leaching results from SGLP and TCLP is shown in Figure 4. 

Results presented in Figure 4 show that neither of these short-term leaching tests resulted in a 

consistently higher or lower leachate concentration, indicating that neither test should be 

considered a more aggressive test. 

 Figure 5 summarizes all available mercury leaching data for FGD materials. As noted, only 

a single sample with baseline FGD material and paired FGD material with mercury control is 

represented. In addition, samples of FGD gypsum collected at a single bituminous-fired facility 

with SCR on and off are also called out in Figure 5. Studies have shown that the speciation of 

mercury in the flue gas can be impacted by SCR systems, but as can be noted by the sample 

descriptions in Appendix A, these samples are not “paired” samples because they were collected 

several months apart. The variability of mercury in coal over time has been noted in other studies 

and may be an explanation for the lower total mercury in the sample with SCR on as compared 

to the one with SCR off. These samples are interesting in that they point out the potential for 

erroneous conclusions if samples without mercury control are compared one-to-one with samples 

Figure 2. Total mercury vs. short- and long-term leachable mercury: all available paired fly ash 

samples. One paired sample set has two fly ash – with mercury control samples. 
7 

Figure 3. Total mercury vs. SGLP leachable mercury: all available paired fly ash samples. One 

paired sample set has two fly ash – with mercury control samples. 

Figure 4. Total mercury vs. SGLP and TCLP leachable mercury: all available paired fly ash 

samples. One paired sample set has two fly ash – with mercury control samples. 
8 

Figure 5. Total mercury vs. short- and long-term leachable mercury: all FGD material samples. 

with mercury control, unless these samples are a true baseline sample and a paired sample with

mercury control. Since many FGD materials exhibit a near-neutral pH, only a few FGD materials 

tested included LTL data points. 

 Based on the mercury leaching data currently available from this project, the following 

preliminary observations were made: 

• Total mercury content of samples generated both with and without mercury emission 

controls present and leachate concentrations did not correlate. 

• Leachate concentrations were independent of short-term leaching procedures used. 

• Leachate mercury concentrations have been found to be extremely low regardless of 

the total mercury content of the sample. Most leachates exhibited mercury 

concentrations less than the reporting limit of 0.01 μg/L. All leachate concentrations 

fell well below the primary drinking water (PDW) limit of 2.0 μg/L for mercury as 

well as the limit at 30 × PDW (60 μg/L) and 100 × PDW (200 μg/L). 

• Total mercury content of paired test fly ash samples with mercury control was 

consistently higher than the paired baseline fly ash sample without mercury control.
9 

 Other Air Toxic Element Leaching Results 

 The other air toxic elements of interest for this project were arsenic, cadmium, chromium, 

lead, nickel, and selenium. SGLP and LTL only were evaluated for these elements because, as 

already noted, TCLP was only done on submitter request. 

Arsenic 

 Figure 6 shows a comparison of the total arsenic concentrations versus the leachate arsenic 

concentrations for all fly ash samples without and with mercury control. The fly ash samples 

without and with mercury control contained similar concentrations of total arsenic and generally 

leached similar levels of arsenic. Leaching results from baseline fly ash and paired fly ash with

mercury control are shown in Figure 7. The presence of activated carbon in the samples 

designated as with mercury control does not correlate with a higher total arsenic concentration 

for this limited sample set. The FGD material data shown in Figure 8 may indicate that FGD 

materials with higher total arsenic concentrations may leach higher levels of arsenic; however, 

the sample set is too small to draw a firm conclusion. Data on the paired sample set are very 

similar and within the error of the experiments and analytical procedures, so no conclusions can 

be drawn based on those data points. Figure C-3 shows that the long-term leachates exhibited 

lower arsenic concentrations than the SGLP, and this trend can also be seen in Figure C-4. 

Figure 6. Total arsenic vs. short- and long-term leachable arsenic: all fly ash – without mercury 

control and fly ash – with mercury control samples. 
10 

Figure 7. Total arsenic vs. SGLP leachable arsenic: all available paired fly ash samples. 

Figure 8. Total arsenic vs. short- and long-term leachable arsenic: all FGD material samples. One 

sample had a total arsenic LLQ higher than the reported value of another sample. 
11 

Cadmium 

 Figures 9–11 are results of cadmium leaching, with Figure 9 including all samples of fly 

ash without and with mercury control and Figure 10 comparing the baseline fly ash with the 

paired fly ash with mercury control. Figure 11 shows the data on the FGD materials evaluated. 

Results are similar to those noted for arsenic, with no indication that higher levels of cadmium 

are found in samples with activated carbon present and the limited data on the paired sample set 

varying within the limits of the test and analysis. As can be seen in Figure C-5, the three values 

reading above the LLQ for cadmium were from the SGLP. Remaining data points were at the 

LLQ. 

Chromium 

 Figure 12, comparing all fly ash samples for total chromium versus leachate chromium, 

shows that there appears to be an increased chromium leachate concentration for some fly ash 

samples with mercury control. Figure 13, showing the SGLP data for the paired fly ash sample 

sets, also indicates a small increase in chromium leachate concentrations for two sample sets. 

The third sample set has an unusually high LLQ and cannot be used to confirm or refute this 

observation. However, in Figure C-7, it can be noted that the long-term chromium leachate 

concentrations were significantly lower than those for the SGLP for two samples. The third 

sample did show a slightly higher total chromium concentration for the paired fly ash with

mercury control and subsequent slightly higher leachate concentrations for the long-term 

Figure 9. Total cadmium vs. short- and long-term leachable cadmium: all fly ash – without

mercury control and fly ash – with mercury control samples. 
12 

Figure 10. Total cadmium vs. SGLP leachable cadmium: all available paired fly ash samples. 

Figure 11. Total cadmium vs. short- and long-term leachable cadmium: all FGD material 

samples. 
13 

Figure 12. Total chromium vs. short- and long-term leachable chromium: all fly ash – without

mercury control and fly ash – with mercury control samples. Several samples had a leachable 

chromium LLQ higher than the reported values of other samples. 

Figure 13. Total chromium vs. SGLP leachable chromium: all available paired fly ash samples. 

One paired sample set had a leachable chromium LLQ higher than the reported values of other 

samples. 
14 

leaching tests. A reduced y-axis on Figure C-8 shows this in detail; however, the SGLP values 

cannot be used in this evaluation because they are below the LLQ, as noted in the figure. 

Figure 14 shows the data on the FGD materials evaluated. 

Lead 

 As shown in Figures 15 through 17, leachate lead concentrations were below the LLQ for 

most samples evaluated. It can be seen in Figure C-10 and C-11 that for one of the paired fly ash 

samples, the long-term leachate lead concentrations were well above the LLQ. 

Nickel 

 Data for total nickel content versus leachate nickel content in Figure 18 for all fly ash 

samples appears to indicate that those samples containing activated carbon (with mercury 

control) exhibit reduced leaching of nickel, but the data in Figures 19 and C-13 through C-15 

showing comparisons of the paired fly ash samples are insufficient to support this observation. 

Figure 20 shows no correlation between total and leachable nickel for FGD materials. 

Figure 14. Total chromium vs. short- and long-term leachable chromium: all FGD material 

samples. 
15 

Figure 15. Total lead vs. short- and long-term leachable lead: all fly ash – without mercury 

control and fly ash – with mercury control samples. 

Figure 16. Total lead vs. SGLP leachable lead: all available paired fly ash samples. 
16 

Figure 17. Total lead vs. short- and long-term leachable lead: all FGD material samples. 

Figure 18. Total nickel vs. short- and long-term leachable nickel: all fly ash – without mercury 

control and fly ash – with mercury control samples. Several samples had a leachable nickel LLQ 

higher than the reported values of other samples. The x-axis is reduced from 300 μg/g. 
17 

Figure 19. Total nickel vs. SGLP leachable nickel: all available paired fly ash samples. One 

paired sample set had a leachable nickel LLQ higher than the reported values of other samples. 

Figure 20. Total nickel vs. short- and long-term leachable nickel: all FGD material samples. 
18 

Selenium 

 Figures 21 and 22 show the comparative concentrations for total selenium and leachate 

selenium for fly ash samples with Figure 21 showing data points for all fly ash samples and 

Figure 22 showing SGLP results for the paired fly ash samples. Figure 23 contains data on the 

FGD materials evaluated including one paired sample. The selenium data are under continuing 

review, but preliminary interpretive efforts show similar total concentrations and leachate 

concentrations for fly ash regardless of the origin of the sample. Repeat analyses of selected 

samples for total selenium and leaching will be performed. 

Figure 21. Total selenium vs. short- and long-term leachable selenium: all fly ash – without

mercury control and fly ash – with mercury control samples. The x-axis is reduced from 450 

μg/g. The y-axis is reduced from 9000 μg/g. 
19 

Figure 22. Total selenium vs. SGLP leachable selenium: all available paired fly ash samples. 

Figure 23. Total selenium vs. short- and long-term leachable selenium: all FGD material 

samples. 
20 

SUMMARY 

 The data presented in this report include all leaching data for the project entitled “Mercury 

and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization.” The 

most complete data set is for the element mercury, and the data presented support the following 

preliminary conclusions: 

• Total mercury content of samples generated both with and without mercury emission 

controls present and leachate concentrations did not correlate. 

• Leachate concentrations were independent of short-term leaching procedures used. 

• Leachate mercury concentrations have been found to be extremely low regardless of 

the total mercury content of the sample. Most leachates exhibited mercury 

concentrations less than the reporting limit of 0.01 μg/L. All leachate concentrations 

fell well below the PDW limit of 2.0 μg/L for mercury as well as the limit at 30 × 

PDW (60 μg/L) and 100 × PDW (200 μg/L). 

• Total mercury content of paired test fly ash samples with mercury control was 

consistently higher than the paired baseline fly ash sample without mercury control.

 For the remaining air toxic elements, the following preliminary observations can be made: 

• The presence of activated carbon in fly ash samples with mercury control is not an 

indicator of increased total concentrations of any of the air toxic elements studied. The 

data from a limited number of paired fly ash samples support this observation. 

• Generally, higher total concentrations of air toxic elements do not correlate to higher 

leachate concentrations. 

• All air toxic elements showed reduced, increased, or variable leachate concentrations 

with increased time using the SGLP and LTL tests. Based on previous EERC work, 

these leaching profiles are expected to be sample-dependent. 

 Continuing work on leaching in this project will focus on adding leaching data from FGD 

materials and paired samples of both fly ash and FGD materials. Data verification will also be 

completed for inclusion in the project final report. The results of an interlaboratory comparison 

of leaching methods will also be completed by the conclusion of this project, and results of that 

study will be reported in the project final report. 

REFERENCES 

1. Kim, A.G. CCB Leaching Summary: Survey of Methods and Results. In Proceedings of Coal 

Combustion By-Products and Western Coal Mines: A Technical Interactive Forum; Golden, 

CO, April 16–18, 2002. 
21 

2. Sorini, S.S. An Overview of Leaching Methods and Their Application to Coal Combustion 

By-Products. In Proceedings of the 12th International Symposium on the Management and 

Use of Coal Combustion Products (CCPs); Orlando, FL, Jan 26–30, 1997. 

3. Kim, A.G. Results of CUB Leaching Studies: Metal Solubility. In Proceedings of the 15th 

International Symposium on the Management and Use of Coal Combustion Products (CCPs); 

St. Petersburg, FL, Jan 27–30, 2003. 

4. Hassett, D.J. The Synthetic Groundwater Leaching Procedure. In Encyclopedia of 

Environmental Analysis and Remediation; Meyers, R.A., Ed.; John Wiley and Sons: New 

York, 1998; pp 4797–4803. 

5. USEPA Method 1311, Toxicity Characteristic Leaching Procedure, Test Methods for 

Evaluating Solid Waste, Physical/Chemical Methods, EPA Publication SW-846, Third 

Edition, as amended by Updates I, II, IIB, and III, finalized in the Federal Register on June 

13, 1997. 

6. Kosson, D.S.; van der Sloot, H.A.; Sanchez, F.; Garrabrants, A.C. An Integrated Framework 

for Evaluating Leaching in Waste Management and Utilization of Secondary Materials. 

Environmental Engineering Science 2002, 19 (3), 159–203. 

7. American Society for Testing and Materials. Standard Test Method for Shake Extraction of 

Solid Waste with Water. In Annual Book of ASTM Standards; Section 11: Water and 

Environmental Technology, ASTM D3987-85, 2004. 
APPENDIX A 

Hg/ATE PROJECT SAMPLE SET AND ANALYSIS 

STATUS 
Hg/ATE Project Sample Set and Analysis Status

pH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.

ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total Total Trace SGLP 30-day LTL 60-

02-002 Fly ash Eastern bituminous Yes 30.6 3.62 24.2% Completed IS Completed pH 02-003 Fly ash Eastern bituminous Yes 21.7 3.91 19.3% Completed LP Completed pH 02-004 Fly ash Subbituminous Yes 5.50 11.47 IS Completed IS Completed Completed Co02-005 Fly ash Subbituminous Yes 4.73 10.65 IS Completed IS Completed Completed Co02-006 Fly ash Subbituminous Yes 5.81 10.86 3.88% Completed Completed Completed IS 02-007 Fly ash Eastern bituminous Yes 120 3.54 24.3% Completed LP Completed pH 02-069 Fly ash Eastern bituminous Yes 0.526 8.94 12.6% Completed Completed Completed pH 02-070 Fly ash Eastern bituminous No 0.197 10.25 5.85% Completed Completed Completed Pending P02-071 Fly ash Eastern bituminous Yes 0.595 9.59 17.2% Completed Completed Completed pH 02-072 Fly ash Eastern bituminous No 0.158 10.35 5.18% Completed Completed Completed Pending P02-073 Fly ash Eastern bituminous No 0.205 12.56 5.00% Completed Completed Completed Pending P02-074 Fly ash Eastern bituminous No 0.526 12.18 6.09% Completed Completed Completed Pending P02-076 Fly ash Eastern bituminous Yes 0.400 9.93 21.0% Completed LP Completed pH 03-004 Fly ash Eastern bituminous No 0.0973 4.26 3.20% Completed Completed Completed pH Co03-005 Fly ash Eastern bituminous No 0.0842 4.26 3.59% Completed Completed Completed pH Co03-006 Fly ash Eastern bituminous No 0.194 4.60 5.28% Completed Completed Completed pH Co03-007 Fly ash Eastern bituminous No 0.141 4.15 4.41% Completed Completed Completed pH Co03-008 Fly ash Eastern bituminous No 0.119 11.72 IS Completed IS Completed IS 03-009 Fly ash Eastern bituminous Yes 0.198 11.79 IS Completed IS Completed IS 03-010 Fly ash Eastern bituminous Yes 0.371 10.34 IS Completed IS Completed IS 03-011 Fly ash Unknown Yes 0.618 8.44 10.5% Completed LP Completed pH 03-012 Fly ash Unknown Yes 1.09 11.58 12.8% Completed IS Completed IS 03-013 Fly ash Unknown Yes 0.362 10.39 10.9% Completed LP Completed IS 03-014 Fly ash Unknown Yes 1.21 9.95 10.9% Completed LP Completed NA 03-015 Fly ash Unknown Yes IS 10.52 IS IS IS Completed NA 03-016 Fly ash Lignite No 0.0161 12.60 0.34% Completed Completed Pending Pending P03-017 Fly ash Lignite Yes 0.225 12.57 0.96% Completed Completed LP/Composite LP/Composite LP/C03-018 Fly ash Lignite Yes 0.289 12.57 0.97% Completed Completed LP/Composite LP/Composite LP/C03-019 Fly ash Lignite Yes 2.22 11.74 4.21% Completed Completed LP/Composite LP/Composite LP/C03-060 Fly ash Subbituminous Yes 1.86 11.32 2.28% Completed Completed Completed Completed Co03-061 Fly ash Subbituminous No 0.578 12.02 1.00% Completed Completed Completed Completed Co03-062 Fly ash Lignite Yes 0.490 12.57 1.29% Completed Completed Completed Completed Co03-063 Fly ash Eastern bituminous No < 0.005 11.30 0.47% Completed Completed Completed Completed Co03-065 Gypsum Eastern bituminous No 0.0440 8.59 1.22% Completed Completed Completed pH Co03-067 FGD Slurry Eastern bituminous No < 0.1 8.05 6.38% Completed Completed Pending pH 03-074 Dust collector ash Lignite No < 0.005 12.63 34.5% Completed Completed Completed NA – low Hg Co03-075 Fly ash Lignite No 1.40 12.70 15.4% Completed Completed Completed Completed Co03-076 Fly ash Lignite No 0.553 12.71 21.5% Completed Completed Completed Completed Co03-077 Fly ash Lignite No 2.03 11.85 IS Completed Completed Completed Completed Co03-078 Fly ash Lignite No 0.662 11.59 IS Completed IS Completed IS 03-079 Fly ash Lignite No 0.785 11.72 2.54% Completed Completed Completed Completed Co03-080 Fly ash Lignite No 0.440 11.64 7.48% Completed Completed Completed Completed Co03-081 Fly ash Lignite No 0.459 11.26 1.15% Completed Completed Completed Completed Co03-082 FGD filtercake Eastern bituminous No 0.218 7.47 4.20% Completed Completed Completed Completed Co03-083 Fly ash Eastern bituminous No 0.0174 4.28 1.20% Completed Completed Completed pH 03-084 Fixated FGD Eastern bituminous No 0.180 12.52 3.17% Completed Completed Completed Completed Co03-085 Fly ash Eastern bituminous No 0.0337 7.06 2.10% Completed Completed Completed pH 03-086 FGD filtercake Eastern bituminous No 0.162 7.70 5.87% Completed Completed Pending pH 03-087 Fixated FGD Eastern bituminous No 0.136 12.51 3.80% Completed Completed Completed Completed Co03-088 Fly ash Eastern bituminous No 0.0103 7.50 1.07% Completed Completed Completed Completed Co03-089 Gypsum Eastern bituminous No 0.0960 8.22 1.94% Completed Completed Completed pH Co03-103 FGD slurry water Eastern bituminous No Pending 6.73 NA – water Underway Underway NA – water NA – water NA 03-104 FGD Filtercake Water Eastern bituminous No Pending 6.53 NA – water Underway Underway NA – water NA – water NA 

A-1 
Hg/ATE Project Sample Set and Analysis Status

pH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.

ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total Total Trace SGLP 30-day LTL 60-

04-003 Fly ash Eastern bituminous No 0.685 9.34 8.44% Completed Completed Completed Completed Co04-004 Fly ash Eastern bituminous No 0.0411 10.29 1.38% Completed Completed Completed Completed Co04-006 Fly ash Western bituminous No 0.144 11.52 1.42% Completed Completed Completed Completed Co04-007 Fly ash Western bituminous No 0.521 13.00 2.46% Completed Completed Completed Completed Co04-029 Fly ash Subbituminous No 0.261 12.37 0.48% Completed Completed Completed Completed Co04-030 Fly ash Lignite Yes 0.147 11.51 0.70% Completed Completed Completed Completed Co04-031 Fly ash Lignite Yes 0.174 11.60 0.64% Completed Completed Completed Completed Co04-032 Fly ash Lignite Yes 0.470 9.67 1.09% Completed Completed Completed pH 04-033 Fly ash Lignite Yes 1.43 10.70 1.27% Completed Completed Completed Completed Co04-034 Fly ash Unknown No 0.424 11.92 29.3% Completed Underway Completed Completed Co04-035 Fly ash Lignite No 0.159 12.68 2.24% Completed Completed Completed Completed Co04-036 Fly ash Lignite Yes 0.287 12.64 2.16% Completed Completed Completed Completed Co04-037 Fly ash Lignite/subbituminous No 0.435 11.80 Pending Completed Pending Pending Pending P04-038 Fly ash Lignite/subbituminous No 0.802 11.72 Pending Completed Pending Pending Pending P04-039 Fly ash Lignite/subbituminous No 0.767 11.32 Pending Completed Pending Pending Pending P04-040 Fly ash Lignite/subbituminous No 0.507 9.58 Pending Completed Pending Pending Pending P04-041 Fly ash Lignite/subbituminous No 0.287 IS IS Completed Pending IS IS 04-042 Fly ash Lignite No 0.371 11.77 Pending Completed Pending Pending Pending P04-043 Fly ash Lignite No 0.689 11.48 Pending Completed Pending Pending Pending P04-044 Fly ash Lignite No 0.878 11.52 Pending Completed Pending Pending Pending P04-045 Fly ash Lignite No 0.849 IS IS Completed Pending Pending IS 04-054 Fly ash Eastern bituminous Yes 17.7 6.40 18.6% Completed Completed Completed NA 04-055 Field – fly ash Lignite No 0.0070 Pending 5.73% Completed Pending Pending Pending P04-056

Field – wet FGD/Mill 

Rejects Lignite No 0.187 Pending 3.31% Completed Pending Pending Pending P

04-057

Field – Wet FGD/mill 

rejects Lignite No 0.207 Pending 2.18% Completed Pending Pending Pending P

04-058 Field – soil Lignite No 0.0500 Pending 6.88% Completed Pending Pending Pending P04-059 Field – bottom ash Lignite No 0.0440 Pending 1.99% Completed Pending Pending Pending P04-060 Field – wet FGD Lignite No 0.299 Pending 2.49% Completed Pending Pending Pending P04-061 Field – bottom ash Lignite No < 0.005 Pending 13.0% Completed Pending Pending Pending P04-062 Field – bottom ash Lignite No < 0.005 Pending 7.73% Completed Pending Pending Pending P04-063 Field – FGD/fly ash Lignite No 0.0800 Pending 3.40% Completed Pending Pending Pending P04-064 Field – FGD/fly ash Lignite No 0.250 Pending 2.68% Completed Pending Pending Pending P04-065 Field – FGD/fly ash Lignite No 0.0110 Pending 3.68% Completed Pending Pending Pending P04-067 Fly ash Subbituminous Yes 0.640 12.80 2.11% Completed Completed Underway Pending P04-082 FGD gypsum Eastern bituminous No 0.0430 8.10 1.60% Completed Completed Underway pH 04-083 FGD gypsum Eastern bituminous No 0.103 8.10 2.26% Completed Completed Underway pH 05-001 Fly ash Lignite No < 0.005 12.84 0.90% Completed Completed Underway Pending P05-002 FGD–SDA Lignite No < 0.005 12.85 0.95% Completed Completed Underway Pending P05-003 Fly ash Lignite Yes 0.565 12.85 1.04% Completed Completed Underway Pending P05-004 FGD–SDA Lignite Yes 0.332 13.06 1.12% Completed Completed Underway Pending P05-005 Fly ash Lignite No 0.431 Pending Pending Completed Pending Underway Pending P05-006 FGD slurry Lignite No Pending Pending Pending Pending Pending Pending Pending P05-007 FGD slurry water Lignite No Underway Pending NA Underway Underway NA – water NA – water NA 

99-188 Fly ash + FGD–SDA Subbituminous No 0.112 12.34 2.07% Completed Completed Completed Completed Co

A-2
APPENDIX B 

TABLES 
B-1 

Table B-1. Fly Ash Arsenic Data 

ID No. Hg Control As, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 37.4 3.5 NT* NT NT

03-004 No 72.2 7.7 NT 118 NT

03-005 No 71.4 4.4 NT 6.5 NT

03-006 No 78 19.2 NT 110 NT

03-007 No 70.4 20 NT 10.6 NT

03-011 Yes NT NT NT NT 1482

03-060 Yes 19.4 2.7 <2 <2 NT

03-061 No 43.5 2 <2 <2 NT

03-062 Yes 43.3 6.6 <2 5.2 NT

03-063 No 45.5 67.8 37.7 36.1 NT

03-075 No 42.2 5.4 20.3 26 NT

03-076 No 25.6 3.3 5.2 12.2 NT

03-077 No 36.8 18.4 7.6 10.8 NT

03-078 No NT 95.1 NT NT NT

03-079 No 351 75.7 45.3 54.6 NT

03-080 No 157 44.6 35.2 29.0 NT

03-081 No 492 140 232 224 NT

03-083 No 166 97.3 NT NT NT

03-085 No 145 266 NT NT NT

03-088 No 44 18.4 23 23.4 NT

04-003 No 46 188 305 309 NT

04-004 No 31.5 136 135 140 NT

04-006 No 5.9 12.3 3.4 7.3 NT

04-007 No 7.09 10.7 <2 <2 NT

04-029 No 31.1 <2 <2 <2 NT

04-030 Yes 136 26.9 8.1 10.6 NT

04-031 Yes 134 23.2 9.6 11.5 NT

04-032 Yes 161 28 NT NT NT

04-033 Yes 148 31.1 10.1 10.4 NT

04-034 No NT 30.8 15.2 16.0 NT

04-035 No 36 <2 <2 <2 NT

04-036 Yes 44.9 <2 <2 <2 NT

04-054 Yes 444 842 NT NT NT

04-067 Yes 26.8 15.2 NT NT NT

05-001 No 24.4 3 NT NT NT

05-003 Yes 28.6 7.2 NT NT NT

05-005 No NT 134 NT NT NT

*=Not tested. 
B-2 

 Table B-2. Fly Ash Cadmium Data 

ID No. Hg Control Cd, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 1.97 <0.2 NT NT NT

03-004 No <1 6.27 NT 1.11 NT

03-005 No <1 7.72 NT 7.22 NT

03-006 No 1.36 4.31 NT 1.37 NT

03-007 No <1 7.83 NT 6.7 NT

03-011 Yes NT NT NT NT 27.4

03-060 Yes 1.87 <0.2 <0.2 <0.2 NT

03-061 No 1.72 <0.2 <0.2 <0.2 NT

03-062 Yes <1 0.34 <0.2 <0.2 NT

03-063 No <1 <0.2 0.64 0.61 NT

03-075 No 1.47 <0.2 0.42 0.51 NT

03-076 No <1 <0.2 0.25 0.29 NT

03-077 No 2.82 0.35 0.21 <0.2 NT

03-078 No NT 0.43 NT NT NT

03-079 No 2.1 0.37 4.23 4.18 NT

03-080 No 1.06 1.57 1.97 2.10 NT

03-081 No 3.6 3.75 6.02 5.49 NT

03-083 No 3.57 <0.2 NT NT NT

03-085 No 2.55 0.28 NT NT NT

03-088 No 8.59 4.93 7.64 8.3 NT

04-003 No <1 0.56 0.88 0.74 NT

04-004 No <1 0.7 1.02 0.84 NT

04-006 No <1 0.28 0.36 0.33 NT

04-007 No <1 <0.2 <0.2 <0.2 NT

04-029 No 1.07 <0.2 <0.2 <0.2 NT

04-030 Yes 3.34 1.4 1.86 2.35 NT

04-031 Yes 3.24 1.49 1.95 2.34 NT

04-032 Yes 3.38 1.24 NT NT NT

04-033 Yes 2.91 1.32 1.99 2.46 NT

04-034 No NT 0.217 0.27 0.5 NT

04-035 No <1 <0.2 <0.2 <0.2 NT

04-036 Yes <1 0.27 <0.2 <0.2 NT

04-054 Yes 1.16 1.87 NT NT NT

04-067 Yes 0.942 0.39 NT NT NT

05-001 No 0.669 0.24 NT NT NT

05-003 Yes 0.755 0.3 NT NT NT

05-005 No NT 2.79 NT NT NT
B-3 

Table B-3. Fly Ash Chromium Data 

ID No. Hg Control Cr, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 111 560 NT NT NT

03-004 No 142 <50 NT 10.1 NT

03-005 No 148 <2 NT <2 NT

03-006 No 135 <50 NT 7.5 NT

03-007 No 137 <50 NT <2 NT

03-011 Yes NT NT NT NT 437

03-060 Yes 76.7 <50 6.3 10.7 NT

03-061 No 67.6 <50 3 3.2 NT

03-062 Yes 54.4 80 3.6 5.2 NT

03-063 No 128 <50 38.6 38.8 NT

03-075 No 26.1 <2 <2 <2 NT

03-076 No 25.5 <2 <2 <2 NT

03-077 No 17.1 <50 16.1 <2 NT

03-078 No NT 150 NT NT NT

03-079 No 83.2 150 265 263 NT

03-080 No 66.1 90 134 122 NT

03-081 No 85.2 120 264 252 NT

03-083 No 137 <50 NT NT NT

03-085 No 124 <50 NT NT NT

03-088 No 160 110 160 180 NT

04-003 No 135 48.8 69.3 70.3 NT

04-004 No 144 70 98.1 100 NT

04-006 No 43.8 34.6 49.2 52.8 NT

04-007 No 64.9 120 7.3 6.7 NT

04-029 No 63.7 24.1 5.1 2.3 NT

04-030 Yes 92.8 399 640 670 NT

04-031 Yes 91.8 410 650 680 NT

04-032 Yes 94.8 333 NT NT NT

04-033 Yes 86.5 351 580 620 NT

04-034 No NT 29.5 62.5 83.3 NT

04-035 No 55.4 55.8 <2 2.1 NT

04-036 Yes 48.8 67.6 <2 2.1 NT

04-054 Yes 115 17.3 NT NT NT

04-067 Yes 44.8 <2 NT NT NT

05-001 No 45.1 45.3 NT NT NT

05-003 Yes 45.5 49.9 NT NT NT

05-005 No NT 137 NT NT NT
B-4 

Table B-4. Fly Ash Lead Data 

ID No. Hg Control Pb, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 60.2 <2 NT NT NT

03-004 No 65.4 <2 NT <2 NT

03-005 No 72.6 <2 NT <2 NT

03-006 No 94.3 <2 NT <2 NT

03-007 No 80.7 <2 NT <2 NT

03-011 Yes NT NT NT NT 37.4

03-060 Yes 82.2 <2 3 2.4 NT

03-061 No 59.5 <2 3.6 8.5 NT

03-062 Yes 30.3 <2 <2 <2 NT

03-063 No 37.1 <2 <2 <2 NT

03-075 No 58.9 <2 2.9 2.1 NT

03-076 No 17 <2 <2 <2 NT

03-077 No 137 2.6 <2 <2 NT

03-078 No NT <2 NT NT NT

03-079 No 68.3 <2 <2 <2 NT

03-080 No 39.9 <2 <2 <2 NT

03-081 No 124 <2 <2 <2 NT

03-083 No 265 <2 NT NT NT

03-085 No 247 <2 NT NT NT

03-088 No 249 <2 <2 <2 NT

04-003 No 60.5 <2 <2 <2 NT

04-004 No 55.7 <2 <2 <2 NT

04-006 No 38.8 <2 <2 <2 NT

04-007 No 29.1 <2 2.2 <2 NT

04-029 No 38.6 <2 <2 <2 NT

04-030 Yes 85.3 <2 <2 <2 NT

04-031 Yes 83.4 <2 <2 <2 NT

04-032 Yes 74.9 <2 NT NT NT

04-033 Yes 74.9 <2 <2 <2 NT

04-034 No NT <1 <1 <1 NT

04-035 No 21.9 <2 <2 <2 NT

04-036 Yes 18.7 3 <2 <2 NT

04-054 Yes 49 <2 NT NT NT

04-067 Yes 25.9 2.2 NT NT NT

05-001 No 17.4 <2 NT NT NT

05-003 Yes 21.2 <2 NT NT NT

05-005 No NT <2 NT NT NT
B-5 

Table B-5. Fly Ash Mercury Data 

ID No. Hg Control Hg, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-002 Yes 30.6 <0.01 NT NT <0.01 

02-003 Yes 21.7 <0.01 NT NT <0.01 

02-004 Yes 5.5 <0.01 <0.01 <0.01 <0.01 

02-005 Yes 4.73 <0.01 <0.01 0.01 <0.01 

02-006 Yes 5.81 0.064 NT NT <0.01 

02-007 Yes 120 <0.01 NT NT NT 

02-069 Yes 0.526 0.03 NT NT 0.07 

02-070 No 0.197 0.01 NT NT 0.03 

02-071 Yes 0.595 0.01 NT NT <0.01 

02-072 No 0.158 0.02 NT NT 0.02 

02-073 No 0.205 0.05 NT NT 0.02 

02-074 No 0.526 0.01 NT NT <0.01 

02-076 Yes 0.4 0.016 NT NT <0.01 

03-004 No <0.1 <0.01 NT 0.012 NT 

03-005 No <0.1 0.01 NT 0.239 NT 

03-006 No 0.194 <0.01 NT 0.06 NT 

03-007 No 0.141 <0.01 NT <0.01 NT 

03-008 No 0.119 <0.01 NT NT 0.034 

03-009 Yes 0.198 <0.01 NT NT <0.01 

03-010 Yes 0.371 <0.01 NT NT <0.01 

03-011 Yes 0.618 <0.01 NT NT 0.17 

03-012 Yes 1.09 <0.01 NT NT <0.01 

03-013 Yes 0.362 <0.01 NT NT <0.01 

03-014 Yes 1.21 0.018 NT NT 0.01 

03-015 Yes NT <0.01 NT NT <0.01 

03-060 Yes 1.86 <0.01 <0.01 0.037 NT 

03-061 No 0.578 <0.01 <0.01 0.325 NT 

03-062 Yes 0.490 <0.01 <0.01 <0.01 NT 

03-063 No <0.1 <0.01 <0.01 0.038 NT 

03-075 No 1.40 0.039 <0.01 0.13 NT 

03-076 No 0.553 0.087 <0.01 0.027 NT 

03-077 No 2.03 <0.01 <0.01 0.054 NT 

03-078 No 0.662 <0.01 NT NT NT 

03-079 No 0.785 <0.01 <0.01 0.02 NT 

03-080 No 0.440 0.011 0.113 0.023 NT 

03-081 No 0.469 0.083 0.013 0.018 NT 

03-083 No <0.1 <0.01 NT NT NT 

03-085 No <0.1 <0.01 NT NT NT 

03-088 No <0.1 0.029 <0.01 <0.01 NT 

04-003 No 0.685 <0.01 0.04 <0.01 NT 

04-004 No <0.1 <0.01 <0.01 0.077 NT 

04-006 No 0.144 <0.01 0.076 0.087 NT 

04-007 No 0.521 0.021 0.035 <0.01 NT 

04-029 No 0.261 0.023 <0.01 <0.01 NT 

04-030 Yes 0.147 <0.01 <0.01 <0.01 NT 

04-031 Yes 0.174 0.012 <0.01 0.028 NT 

04-032 Yes 0.470 <0.01 NT NT NT 

04-033 Yes 1.43 <0.01 <0.01 <0.01 NT 

04-034 No 0.424 <0.2 <0.2 <0.2 NT 

04-035 No 0.159 0.081 0.02 <0.01 NT 

04-036 Yes 0.287 0.016 <0.01 <0.01 NT 

04-054 Yes 17.7 <0.01 NT NT NT 

04-067 Yes 0.640 <0.01 NT NT NT 

05-001 No <0.1 <0.01 NT NT NT 

05-003 Yes 0.565 <0.01 NT NT NT 

05-005 No 0.431 <0.01 NT NT NT 
B-6 

Table B-6. Fly Ash Nickel Data 

ID No. Hg Control Ni, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 50.6 <2 NT NT NT

03-004 No 68.3 50 NT 8.1 NT

03-005 No 85.7 63.2 NT 70 NT

03-006 No 60.4 40 NT 18.2 NT

03-007 No 71.3 50 NT 70 NT

03-011 Yes NT NT NT NT 279

03-060 Yes 67.6 <40 4.5 <2 NT

03-061 No 93.9 <40 4.1 <2 NT

03-062 Yes 57.6 <40 <2 <2 NT

03-063 No 23.3 <40 <2 <2 NT

03-075 No 25.4 <2 <2 <2 NT

03-076 No 24.6 <2 <2 <2 NT

03-077 No 17.8 <40 <2 <2 NT

03-078 No NT <40 NT NT NT

03-079 No 40.9 <40 <2 <2 NT

03-080 No 63.5 <2 <2 <2 NT

03-081 No 68.4 <2 <2 <2 NT

03-083 No 259 <40 NT NT NT

03-085 No 277 <40 NT NT NT

03-088 No 74.5 <2 5.4 5.6 NT

04-003 No 76.6 <2 <2 <2 NT

04-004 No 81.6 <2 <2 <2 NT

04-006 No 26.1 <2 <2 <2 NT

04-007 No 22 <2 10.6 10 NT

04-029 No 39.9 <2 4 4.8 NT

04-030 Yes 24.2 <2 5.6 3.3 NT

04-031 Yes 28.2 <2 4.4 2.9 NT

04-032 Yes 40 <2 NT NT NT

04-033 Yes 29.1 <2 5.8 4.7 NT

04-034 No NT 5.97 4.07 <2 NT

04-035 No 17.2 <2 9.6 6.2 NT

04-036 Yes 23.5 <2 8.2 5.4 NT

04-054 Yes 94.5 5.6 NT NT NT

04-067 Yes 41.5 21 NT NT NT

05-001 No 30.3 43.6 NT NT NT

05-003 Yes 25.7 25.2 NT NT NT

05-005 No NT 15.5 NT NT NT
B-7 

Table B-7. Fly Ash Selenium Data 

ID No. Hg Control Se, μg/g SGLP 30-Day LTL 60-Day LTL TCLP 

02-006 Yes 36.6 57.1 NT NT NT

03-004 No <1 16.7 NT 125 NT

03-005 No <1 14.7 NT 48.9 NT

03-006 No 5.27 48.5 NT 212 NT

03-007 No 0.792 36.6 NT 86.9 NT

03-011 Yes NT NT NT NT 165

03-060 Yes <1 8.4 8.5 11.4 NT

03-061 No 23.4 5.4 9.8 13.9 NT

03-062 Yes <1 68 <2 3.8 NT

03-063 No <1 29.1 42.6 37.4 NT

03-075 No <1 40.3 41.9 41.6 NT

03-076 No <1 19.1 16.6 13.8 NT

03-077 No 3.74 71.6 71.3 69.3 NT

03-078 No NT 151 NT NT NT

03-079 No <1 60.4 40.1 38.3 NT

03-080 No <1 75.1 23.8 23.4 NT

03-081 No <1 240 112 94.9 NT

03-083 No <1 44.1 NT NT NT

03-085 No <1 77.6 NT NT NT

03-088 No <1 76.4 15.5 19 NT

04-003 No 3.39 412 489 503 NT

04-004 No <1 166 186 180 NT

04-006 No <1 160 111 76.2 NT

04-007 No <1 265 26.7 17.4 NT

04-029 No <1 2.1 <2 <2 NT

04-030 Yes <1 222 53.2 63.4 NT

04-031 Yes <1 177 54.4 60.3 NT

04-032 Yes 5.41 215 NT NT NT

04-033 Yes 5.67 156 64.8 71 NT

04-034 No NT 113 12.8 21.1 NT

04-035 No <1 17.8 <2 <2 NT

04-036 Yes <1 19.9 <2 <2 NT

04-054 Yes 428 8620 NT NT NT

04-067 Yes 7.59 47.2 NT NT NT

05-001 No 3.38 12.9 NT NT NT

05-003 Yes 5.08 34.2 NT NT NT

05-005 No NT 123 NT NT NT
B-8 

Table B-8. FGD Material Arsenic Data 

ID No. Hg Control As, ug/g SGLP 30-Day LTL 60-Day LTL

99-188 No 14.7 3.5 2.6 2.2

03-065 No <1 <2 NT <2

03-082 No <1 3.7 3.5 <2

03-084 No 53.4 4.9 5.2 <2

03-087 No 53.8 7 24 19.1

03-089 No <1 <2 NT <2

04-082 No 1.65 <2 NT NT

04-083 No <2 <2 NT NT

05-002 No 22.6 2.1 NT NT

05-004 Yes 21.8 4.3 NT NT

Table B-9. FGD Material Cadmium Data 

ID No. Hg Control Cd, ug/g SGLP 30-Day LTL 60-Day LTL 

99-188 No <1 0.37 0.58 0.59 

03-065 No <1 <0.2 NT <0.2 

03-082 No <1 <0.2 0.83 0.47 

03-084 No 1.24 0.44 0.66 0.49 

03-087 No 1.08 0.43 0.3 0.37 

03-089 No 1.89 0.46 NT <0.2 

04-082 No <0.5 0.33 NT NT 

04-083 No <0.5 0.25 NT NT 

05-002 No 0.703 0.22 NT NT 

05-004 Yes 0.629 0.2 NT NT 

Table B-10. FGD Material Chromium Data 

ID No. Hg Control Cr, ug/g SGLP 30-Day LTL 60-Day LTL 

99-188 No 26.3 111 215 223 

03-065 No 2.9 <2 NT <2 

03-082 No 10.4 <2 <2 <2 

03-084 No 53.6 4.7 3.1 2.45 

03-087 No 51.6 3 2.2 3.3 

03-089 No 4.13 <2 NT <2 

04-082 No 3.39 <2 NT NT 

04-083 No 3.95 <2 NT NT 

05-002 No 42.8 34.6 NT NT 

05-004 Yes 37.3 21.8 NT NT 
B-9 

Table B-11. FGD Material Lead Data 

ID No. Hg Control Pb, μg/g SGLP 30-Day LTL 60-Day LTL 

99-188 No 37 <2 <2 <2 

03-065 No <1 <2 NT <2 

03-082 No 2.22 <2 <2 <2 

03-084 No 80.3 14.3 <2 <2 

03-087 No 86.7 6.6 <2 <2 

03-089 No 2.08 <2 NT <2 

04-082 No <2.5 <2 NT NT 

04-083 No <2.5 <2 NT NT 

05-002 No 18.6 <2 NT NT 

05-004 Yes 20.9 <2 NT NT 

Table B-12. FGD Material Mercury Data 

ID No. Hg Control Hg, μg/g SGLP 30-Day LTL 60-Day LTL 

99-188 No 0.112 <0.01 <0.01 0.0428

03-065 No <0.1 <0.01 NT <0.01

03-082 No 0.218 0.404 <0.01 <0.01

03-084 No 0.18 0.289 <0.01 <0.01

03-087 No 0.136 0.237 <0.01 <0.01

03-089 No <0.1 <0.01 NT <0.01

04-082 No <0.1 <0.01 NT NT

04-083 No 0.103 <0.01 NT NT

05-002 No <0.1 <0.01 NT NT

05-004 Yes 0.332 <0.01 NT NT

 Table B-13. FGD Material Nickel Data

ID No. Hg Control Ni, μg/g SGLP 30-Day LTL 60-Day LTL 

99-188 No 12.9 21.7 <2 <2

03-065 No <1 <2 NT 10.1

03-082 No 3.5 7.4 32.1 25.4

03-084 No 87.2 <2 4 3.6

03-087 No 98.7 <2 <2 2.1

03-089 No <1 <2 NT 12.6

04-082 No 6.83 28.4 NT NT

04-083 No 6.81 23.3 NT NT

05-002 No 29.7 39.1 NT NT

05-004 Yes 25.3 29.3 NT NT
B-10 

 Table B-14. FGD Material Selenium Data

ID No. Hg Control Se, μg/g SGLP 30-Day LTL 60-Day LTL 

99-188 No <1 47.9 53.5 53.1

03-065 No <1 3.3 NT 2.7

03-082 No <1 71.2 55.2 45.3

03-084 No <1 2.7 2.4 1.5

03-087 No <1 2.1 3.4 <2

03-089 No <1 9.4 NT 8.2

04-082 No <2.5 12.5 NT NT

04-083 No <2.5 18.7 NT NT

05-002 No 4.13 11.3 NT NT

05-004 Yes 3.71 24.3 NT NT
APPENDIX C 

FIGURES 
C-1 

Figure C-1. Total mercury vs. short- and long-term leachable mercury: paired fly ash sample set ID 

Nos. 03-060 and 03-061. 

Figure C-2. Total mercury vs. short- and long-term leachable mercury: paired fly ash sample set ID 

Nos. 04-035 and 04-036. 
C-2 

Figure C-3. Total arsenic vs. short- and long-term leachable arsenic: all available paired fly ash 

samples. 

Figure C-4. Total arsenic vs. short- and long-term leachable arsenic: paired fly ash sample set 

ID Nos. 03-060 and 03-061. 
C-3 

Figure C-5. Total cadmium vs. short- and long-term leachable cadmium: all available paired fly ash 

samples. 

Figure C-6. Total cadmium vs. short- and long-term leachable cadmium: paired fly ash sample set 

ID Nos. 03-060 and 03-061. 
C-4 

Figure C-7. Total chromium vs. short- and long-term leachable chromium: all available paired fly ash 

samples. One paired sample set had a leachable chromium LLQ higher than the reported 

values of other samples. 

Figure C-8. Total chromium vs. short- and long-term leachable chromium: paired fly ash sample set ID 

Nos. 03-060 and 03-061. The SGLP leachable chromium LLQ was higher than the 

reported values of the long-term leachates. 
C-5 

Figure C-9. Total chromium vs. short- and long-term leachable chromium: paired fly ash sample set 

ID Nos. 04-035 and 04-036. 

Figure C-10. Total lead vs. short- and long-term leachable lead: all available paired fly ash samples. 
C-6 

Figure C-11. Total lead vs. short- and long-term leachable lead: paired fly ash sample set 

ID Nos. 03-060 and 03-061. 

Figure C-12. Total lead vs. short- and long-term leachable lead: paired fly ash sample set 

ID Nos. 04-035 and 04-036. 
C-7 

Figure C-13. Total nickel vs. short- and long-term leachable nickel: all available paired fly ash 

samples. One paired sample set had a leachable nickel LLQ higher than the reported 

values of other samples. 

Figure C-14. Total nickel vs. short- and long-term leachable nickel: paired fly ash sample set ID Nos. 

03-060 and 03-061. The SGLP leachable nickel LLQ was higher than the reported 

values of the long-term leachates. 
C-8 

Figure C-15. Total nickel vs. short- and long-term leachable nickel: paired fly ash sample set 

ID Nos. 04-035 and 04-036. 

Figure C-16. Total selenium vs. short- and long-term leachable selenium: all available paired fly ash 

samples. 
C-9 

Figure C-17. Total selenium vs. short- and long-term leachable selenium: paired fly ash sample set 

ID Nos. 03-060 and 03-061. 

Figure C-18. Total selenium vs. short- and long-term leachable selenium: paired fly ash sample set 

ID Nos. 04-035 and 04-036 
APPENDIX O 

SUMMARY OF LONG-TERM AMBIENTTEMPERATURE RELEASE DATA 
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

99-188 1 1 1 8 0.112 0% NA No sorption or release99-188 1 1 2 91 0.112 0% NA No sorption or release99-188 1 1 3 95 0.112 0.0000026% 9,864,357 Release 194 99-188 2 1 1 8 0.112 -0.0000281% -77,875 Sorption99-188 2 1 2 91 0.112 -0.000300% -83,232 Sorption99-188 2 1 3 95 0.112 -0.000329% -79,095 Sorption 194 99-456 1 1 1 8 1.39 -0.0000010% -2,189,765 Sorption99-456 1 1 2 91 1.39 -0.0000106% -2,361,255 Sorption99-456 1 1 3 95 1.39 -0.0000118% -2,212,209 Sorption 194 99-456 2 1 1 8 1.39 -0.0000005% -4,568,890 Sorption99-456 2 1 2 91 1.39 -0.0000049% -5,046,768 Sorption99-456 2 1 3 95 1.39 -0.0000055% -4,751,898 Sorption 194 00-048 1 1 1 8 0.361 -0.0000031% -717,111 Sorption00-048 1 1 2 91 0.361 -0.0000293% -850,697 Sorption00-048 1 1 3 95 0.361 -0.0000350% -743,129 Sorption 194 00-048 2 1 1 8 0.361 0% NA No sorption or release00-048 2 1 2 91 0.361 0% NA No sorption or release00-048 2 1 3 95 0.361 0.0000018% 14,313,423 Release 194 01-002 1 1 1 8 0.187 -0.0000026% -853,552 Sorption01-002 1 1 2 91 0.187 -0.0000613% -406,857 Sorption01-002 1 1 3 95 0.187 -0.0000887% -293,589 Sorption 194 01-002 2 1 1 8 0.187 -0.0000069% -319,622 Sorption01-002 2 1 2 91 0.187 -0.0000742% -335,780 Sorption01-002 2 1 3 95 0.187 -0.0000762% -341,639 Sorption 194 01-008 1 1 1 8 1.22 0% NA No sorption or release01-008 1 1 2 91 1.22 0.0000020% 12,496,097 Release01-008 1 1 3 95 1.22 0.0000017% 15,517,310 Release 194 01-008 2 1 1 8 1.22 0% NA No sorption or release01-008 2 1 2 91 1.22 0% NA No sorption or release01-008 2 1 3 95 1.22 0% NA No sorption or release 194 01-011 1 1 1 8 2.55 0% NA No sorption or release01-011 1 1 2 91 2.55 0.0000005% 53,747,404 Release01-011 1 1 3 95 2.55 0.0000002% 146,657,695 Release 194 01-011 2 1 1 8 2.55 0% NA No sorption or release01-011 2 1 2 91 2.55 0.0000005% 47,851,501 Release01-011 2 1 3 95 2.55 0.0000003% 100,452,715 Release 194 03-006 1 1 1 8 0.194 -0.0000047% -468,182 Sorption03-006 1 1 2 91 0.194 -0.0000533% -468,182 Sorption03-006 1 1 3 95 0.194 -0.0000520% -500,495 Sorption 194 03-006 2 1 1 8 0.194 -0.0000038% -572,612 Sorption03-006 2 1 2 91 0.194 -0.0000382% -652,696 Sorption03-006 2 1 3 95 0.194 -0.0000425% -612,832 Sorption 194 03-017 1 1 1 8 0.225 0% NA No sorption or release

Page 1 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

03-017 1 1 2 91 0.225 0.0000029% 8,554,255 Release03-017 1 1 3 95 0.225 0.0000016% 16,430,687 Release 194 03-017 2 1 1 8 0.225 -0.0000041% -532,956 Sorption03-017 2 1 2 91 0.225 -0.0000447% -557,211 Sorption03-017 2 1 3 95 0.225 -0.0000477% -545,382 Sorption 194 03-018 1 1 1 8 0.289 0% NA No sorption or release03-018 1 1 2 91 0.289 0.0000032% 7,890,762 Release03-018 1 1 3 95 0.289 0.0000018% 14,840,697 Release 194 03-018 2 1 1 8 0.289 -0.0000051% -427,244 Sorption03-018 2 1 2 91 0.289 -0.0000565% -440,887 Sorption03-018 2 1 3 95 0.289 -0.0000602% -432,098 Sorption 194 03-060 1 1 1 8 1.86 0% NA No sorption or release03-060 1 1 2 91 1.86 0.0000006% 44,570,210 Release03-060 1 1 3 95 1.86 0.0000002% 170,208,032 Release 194 03-060 2 1 1 8 1.86 0% NA No sorption or release03-060 2 1 2 91 1.86 0.0000012% 20,994,849 Release03-060 2 1 3 95 1.86 0.0000009% 29,253,023 Release 194 03-061 1 1 1 8 0.578 0.0000040% 550,923 Release03-061 1 1 2 91 0.578 0.0000023% 10,729,242 Release03-061 1 1 3 95 0.578 0.0000013% 19,586,941 Release 194 03-061 2 1 1 8 0.578 -0.0000000428% -51,176,729 Sorption03-061 2 1 2 91 0.578 -0.0000165% -1,506,482 Sorption03-061 2 1 3 95 0.578 -0.0000164% -1,590,529 Sorption 194 03-062 1 1 1 8 0.490 0% NA No sorption or release03-062 1 1 2 91 0.490 0.0000026% 9,609,441 Release03-062 1 1 3 95 0.490 0.0000005% 52,785,429 Release 194 03-062 2 1 1 8 0.490 0% NA No sorption or release03-062 2 1 2 91 0.490 0% NA No sorption or release03-062 2 1 3 95 0.490 0.0000004% 58,592,405 Release 194 03-065 1 3 1 7 0.044 0.000137% 13,985 Release03-065 1 3 2 90 0.044 0.00209% 11,794 Release03-065 1 3 3 90 0.044 0.00229% 10,788 Release03-065 1 3 4 44 0.044 0.00185% 6,509 Release03-065 1 3 5 46 0.044 0.000751% 16,778 Release03-065 1 3 6 48 0.044 0.000318% 41,353 Release03-065 1 3 7 43 0.044 0.000420% 28,059 Release03-065 1 3 8 58 0.044 -0.000149% -106,573 Sorption03-065 1 3 9 47 0.044 -0.000142% -90,856 Sorption 473 03-065 2 3 1 7 0.044 0.000189% 10,142 Release03-065 2 3 2 90 0.044 0.000875% 28,181 Release03-065 2 3 3 90 0.044 0.00388% 6,350 Release03-065 2 3 4 44 0.044 0.00421% 2,863 Release03-065 2 3 5 46 0.044 0.00108% 11,624 Release

Page 2 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

03-065 2 3 6 48 0.044 0.000229% 57,433 Release03-065 2 3 7 43 0.044 0.000310% 37,981 Release03-065 2 3 8 58 0.044 0.000341% 46,556 Release03-065 2 3 9 47 0.044 -0.0000260% -494,826 Sorption 473 03-082 1 2 1 7 0.248 0.000773% 2,480 Release03-082 1 2 2 44 0.248 0.0324% 372 Release03-082 1 2 3 46 0.248 0.0251% 501 Release03-082 1 2 4 46 0.248 0.0428% 294 Release03-082 1 2 5 45 0.248 0.0660% 187 Release03-082 1 2 6 58 0.248 0.0577% 275 Release03-082 1 2 7 33 0.248 0.0218% 415 Release03-082 1 2 8 45 0.248 0.0286% 431 Release03-082 1 2 9 47 0.248 0.0272% 473 Release03-082 1 2 10 43 0.248 0.0291% 405 Release03-082 1 2 11 44 0.248 0.0322% 375 Release03-082 1 2 12 46 0.248 0.0435% 290 Release03-082 1 2 13 45 0.248 0.0454% 272 Release03-082 1 2 14 45 0.248 0.0368% 335 Release03-082 1 2 15 59 0.248 0.0673% 240 Release03-082 1 2 16 46 0.248 0.0519% 243 Release 699 03-082 2 2 1 7 0.248 0.0000172% 111,680 Release03-082 2 2 2 44 0.248 0.00525% 2,297 Release03-082 2 2 3 46 0.248 0.00596% 2,115 Release03-082 2 2 4 46 0.248 0.0133% 948 Release03-082 2 2 5 45 0.248 0.0323% 381 Release03-082 2 2 6 58 0.248 0.0388% 409 Release03-082 2 2 7 33 0.248 0.0111% 818 Release03-082 2 2 8 45 0.248 0.0175% 705 Release03-082 2 2 9 47 0.248 0.0186% 694 Release03-082 2 2 10 43 0.248 0.0205% 576 Release03-082 2 2 11 44 0.248 0.0199% 605 Release03-082 2 2 12 46 0.248 0.0284% 443 Release03-082 2 2 13 45 0.248 0.0367% 336 Release03-082 2 2 14 45 0.248 0.0285% 432 Release03-082 2 2 15 59 0.248 0.0496% 326 Release03-082 2 2 16 46 0.248 0.121% 104 Release 699 03-082 3 3 1 7 0.248 0.0000234% 81,978 Release03-082 3 3 2 45 0.248 0.0170% 725 Release03-082 3 3 3 45 0.248 0.0380% 324 Release03-082 3 3 4 47 0.248 0.0489% 263 Release03-082 3 3 5 43 0.248 0.0562% 209 Release03-082 3 3 6 44 0.248 0.0511% 236 Release03-082 3 3 7 46 0.248 0.0766% 165 Release

Page 3 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

03-082 3 3 8 45 0.248 0.0815% 151 Release03-082 3 3 9 45 0.248 0.0643% 192 Release03-082 3 3 10 59 0.248 0.375% 43.1 Release03-082 3 3 11 46 0.248 0.264% 47.7 Release 472 03-082 4 3 1 7 0.248 0.000759% 2,527 Release03-082 4 3 2 45 0.248 0.0426% 289 Release03-082 4 3 3 45 0.248 0.0436% 283 Release03-082 4 3 4 47 0.248 0.0436% 295 Release03-082 4 3 5 43 0.248 0.0481% 245 Release03-082 4 3 6 44 0.248 0.0493% 245 Release03-082 4 3 7 46 0.248 0.0661% 191 Release03-082 4 3 8 45 0.248 0.0798% 154 Release03-082 4 3 9 45 0.248 0.0643% 192 Release03-082 4 3 10 59 0.248 0.227% 71.2 Release03-082 4 3 11 46 0.248 0.202% 62.4 Release 472 03-082 5 3 1 7 0.248 0.000666% 2,878 Release03-082 5 3 2 45 0.248 0.0751% 164 Release03-082 5 3 3 45 0.248 0.0485% 254 Release03-082 5 3 4 47 0.248 0.0492% 262 Release03-082 5 3 5 43 0.248 0.0675% 175 Release03-082 5 3 6 44 0.248 0.0654% 184 Release03-082 5 3 7 46 0.248 0.103% 122 Release03-082 5 3 8 45 0.248 0.138% 89.5 Release03-082 5 3 9 45 0.248 0.0947% 130 Release03-082 5 3 10 63 0.248 0.217% 79.4 Release03-082 5 3 11 46 0.248 0.00652% 1,932 Release 476 03-082 6 3 1 7 0.248 0.0000897% 21,385 Release03-082 6 3 2 45 0.248 0.0685% 180 Release03-082 6 3 3 45 0.248 0.0618% 200 Release03-082 6 3 4 47 0.248 0.0397% 324 Release03-082 6 3 5 43 0.248 0.0625% 188 Release03-082 6 3 6 44 0.248 0.0621% 194 Release03-082 6 3 7 46 0.248 0.109% 115 Release03-082 6 3 8 45 0.248 0.131% 94.0 Release03-082 6 3 9 45 0.248 0.116% 106 Release03-082 6 3 10 63 0.248 0.310% 55.7 Release03-082 6 3 11 46 0.248 0.00210% 5,989 Release 476 04-006 1 2 1 7 0.144 -0.0000048% -396,725 Sorption04-006 1 2 2 90 0.144 -0.0000622% -396,725 Sorption04-006 1 2 3 91 0.144 -0.0000587% -424,930 Sorption 188 04-006 2 2 1 7 0.144 -0.0000089% -214,953 Sorption04-006 2 2 2 90 0.144 -0.000113% -219,087 Sorption04-006 2 2 3 91 0.144 -0.000114% -218,809 Sorption 188 

Page 4 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

04-007 1 2 1 7 0.521 -0.0000020% -958,159 Sorption04-007 1 2 2 90 0.521 -0.0000329% -749,092 Sorption04-007 1 2 3 91 0.521 -0.0000336% -742,965 Sorption 188 04-007 2 2 1 7 0.521 -0.0000007% -2,748,990 Sorption04-007 2 2 2 90 0.521 -0.0000080% -3,093,527 Sorption04-007 2 2 3 91 0.521 -0.0000081% -3,079,637 Sorption 188 04-029 1 3 1 7 0.261 -0.0000006% -3,115,851 Sorption04-029 1 3 2 90 0.261 -0.0000160% -1,542,848 Sorption04-029 1 3 3 90 0.261 -0.0000138% -1,782,759 Sorption 187 04-029 2 3 1 7 0.261 0.0000001% 33,539,583 Release04-029 2 3 2 90 0.261 -0.0000178% -1,382,399 Sorption04-029 2 3 3 90 0.261 -0.0000155% -1,590,153 Sorption 187 04-035 1 2 1 7 0.159 -0.0000026% -750,237 Sorption04-035 1 2 2 90 0.159 -0.0000307% -804,038 Sorption04-035 1 2 3 91 0.159 -0.0000313% -795,294 Sorption 188 04-035 2 2 1 7 0.159 -0.0000030% -630,077 Sorption04-035 2 2 2 90 0.159 -0.0000359% -687,312 Sorption04-035 2 2 3 91 0.159 -0.0000374% -667,237 Sorption 188 04-036 1 2 1 7 0.287 -0.0000005% -3,523,638 Sorption04-036 1 2 2 90 0.287 -0.0000189% -1,301,931 Sorption04-036 1 2 3 91 0.287 -0.0000197% -1,262,661 Sorption 188 04-036 2 2 1 7 0.287 -0.0000017% -1,120,108 Sorption04-036 2 2 2 90 0.287 -0.0000205% -1,205,697 Sorption04-036 2 2 3 91 0.287 -0.0000212% -1,176,251 Sorption 188 04-044 1 3 1 7 0.878 -0.0000010% -1,912,355 Sorption04-044 1 3 2 90 0.878 -0.0000123% -2,012,058 Sorption04-044 1 3 3 90 0.878 -0.0000113% -2,188,197 Sorption 187 04-044 2 3 1 7 0.878 -0.0000003% -5,752,628 Sorption04-044 2 3 2 90 0.878 -0.0000067% -3,663,105 Sorption04-044 2 3 3 90 0.878 -0.0000059% -4,205,365 Sorption 187 04-054 1 2 1 7 17.7 0.0000000% -745,762,297 Sorption04-054 1 2 2 90 17.7 -0.0000004% -60,558,141 Sorption04-054 1 2 3 91 17.7 -0.0000004% -60,699,677 Sorption 188 04-054 2 2 1 7 17.7 0.0000000% -1,390,309,949 Sorption04-054 2 2 2 90 17.7 -0.0000006% -42,001,853 Sorption04-054 2 2 3 91 17.7 -0.0000006% -39,302,048 Sorption 188 04-067 1 2 1 7 0.640 -0.0000010% -2,018,590 Sorption04-067 1 2 2 90 0.640 -0.0000117% -2,114,844 Sorption04-067 1 2 3 91 0.640 -0.0000120% -2,077,249 Sorption 188 04-067 2 2 1 7 0.640 -0.0000011% -1,805,535 Sorption04-067 2 2 2 90 0.640 -0.0000137% -1,805,535 Sorption04-067 2 2 3 91 0.640 -0.0000132% -1,882,177 Sorption 188 04-082 1 4 1 7 0.043 0.161% 11.9 Release

Page 5 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

04-082 1 4 2 7 0.043 0.431% 4.45 Release04-082 1 4 3 7 0.043 0.572% 3.35 Release04-082 1 4 4 5 0.043 0.430% 3.18 Release04-082 1 4 5 7 0.043 0.684% 2.81 Release04-082 1 4 6 3 0.043 0.304% 2.71 Release04-082 1 4 7 5 0.043 0.500% 2.74 Release04-082 1 4 8 5 0.043 0.502% 2.73 Release04-082 1 4 9 4 0.043 0.288% 3.80 Release04-082 1 4 10 5 0.043 0.487% 2.81 Release04-082 1 4 11 5 0.043 0.497% 2.75 Release04-082 1 4 12 4 0.043 0.370% 2.96 Release04-082 1 4 13 5 0.043 0.319% 4.29 Release04-082 1 4 14 6 0.043 0.373% 4.41 Release04-082 1 4 15 13 0.043 0.558% 6.38 Release04-082 1 4 16 7 0.043 0.146% 13.1 Release04-082 1 4 17 7 0.043 0.297% 6.47 Release04-082 1 4 18 9 0.043 0.292% 8.44 Release04-082 1 4 19 14 0.043 0.299% 12.8 Release04-082 1 4 20 29 0.043 0.418% 19.0 Release04-082 1 4 21 46 0.043 0.486% 25.9 Release 200 04-082 2 4 1 7 0.043 0.183% 10.5 Release04-082 2 4 2 7 0.043 0.419% 4.58 Release04-082 2 4 3 7 0.043 0.593% 3.23 Release04-082 2 4 4 5 0.043 0.446% 3.07 Release04-082 2 4 5 7 0.043 0.694% 2.76 Release04-082 2 4 6 3 0.043 0.314% 2.62 Release04-082 2 4 7 5 0.043 0.536% 2.55 Release04-082 2 4 8 5 0.043 0.494% 2.78 Release04-082 2 4 9 4 0.043 0.300% 3.65 Release04-082 2 4 10 5 0.043 0.493% 2.78 Release04-082 2 4 11 5 0.043 0.510% 2.69 Release04-082 2 4 12 4 0.043 0.377% 2.91 Release04-082 2 4 13 5 0.043 0.321% 4.26 Release04-082 2 4 14 6 0.043 0.349% 4.71 Release04-082 2 4 15 13 0.043 0.550% 6.48 Release04-082 2 4 16 7 0.043 0.140% 13.7 Release04-082 2 4 17 7 0.043 0.288% 6.65 Release04-082 2 4 18 9 0.043 0.266% 9.29 Release04-082 2 4 19 14 0.043 0.294% 13.1 Release04-082 2 4 20 29 0.043 0.394% 20.2 Release04-082 2 4 21 46 0.043 0.419% 30.1 Release 200 04-083 1 4 1 7 0.103 0.00272% 706 Release04-083 1 4 2 43 0.103 0.0331% 356 Release

Page 6 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

04-083 1 4 3 45 0.103 0.0563% 219 Release04-083 1 4 4 59 0.103 0.0676% 239 Release04-083 1 4 5 46 0.103 0.221% 56.9 Release 200 04-083 2 4 1 7 0.103 0.00305% 629 Release04-083 2 4 2 43 0.103 0.0609% 194 Release04-083 2 4 3 45 0.103 0.0487% 253 Release04-083 2 4 4 59 0.103 0.0712% 227 Release04-083 2 4 5 46 0.103 0.0986% 128 Release 200 05-001 1 3 1 7 <0.01 -0.000116% -16,506 Sorption05-001 1 3 2 90 <0.01 -0.00116% -21,251 Sorption05-001 1 3 3 90 <0.01 -0.00110% -22,437 Sorption 187 05-001 2 3 1 7 <0.01 -0.000105% -18,212 Sorption05-001 2 3 2 90 <0.01 -0.00196% -12,607 Sorption05-001 2 3 3 90 <0.01 -0.00186% -13,287 Sorption 187 05-002 1 3 1 7 <0.01 -0.000153% -12,503 Sorption05-002 1 3 2 90 <0.01 -0.00275% -8,975 Sorption05-002 1 3 3 90 <0.01 -0.00258% -9,546 Sorption 187 05-002 2 3 1 7 <0.01 0.0000577% 33,230 Release05-002 2 3 2 90 <0.01 -0.000685% -35,990 Sorption05-002 2 3 3 90 <0.01 -0.000562% -43,864 Sorption 187 05-003 1 3 1 7 0.565 -0.0000007% -2,744,055 Sorption05-003 1 3 2 90 0.565 -0.0000131% -1,883,252 Sorption05-003 1 3 3 90 0.565 -0.0000096% -2,578,508 Sorption 187 05-003 2 3 1 7 0.565 0.0000000% 49,463,677 Release05-003 2 3 2 90 0.565 -0.0000044% -5,659,177 Sorption05-003 2 3 3 90 0.565 -0.0000029% -8,416,414 Sorption 187 05-004 1 3 1 7 0.332 -0.0000018% -1,076,757 Sorption05-004 1 3 2 90 0.332 -0.0000320% -769,945 Sorption05-004 1 3 3 90 0.332 -0.0000272% -904,992 Sorption 187 05-004 2 3 1 7 0.332 -0.0000017% -1,151,710 Sorption05-004 2 3 2 90 0.332 -0.0000201% -1,227,580 Sorption05-004 2 3 3 90 0.332 -0.0000192% -1,285,465 Sorption 187 05-009 1 3 1 7 0.032 0.000863% 2,222 Release05-009 1 3 2 45 0.032 0.00672% 1,833 Release05-009 1 3 3 45 0.032 0.00202% 6,102 Release05-009 1 3 4 90 0.032 0.00535% 4,607 Release05-009 1 3 5 44 0.032 0.00817% 1,476 Release05-009 1 3 6 46 0.032 0.000506% 24,928 Release05-009 1 3 7 48 0.032 0.000169% 77,979 Release05-009 1 3 8 43 0.032 0.000117% 100,674 Release05-009 1 3 9 58 0.032 -0.000109% -145,382 Sorption05-009 1 3 10 47 0.032 0.000056% 230,325 Release 473 05-009 2 3 1 7 0.032 0.000816% 2,351 Release

Page 7 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

05-009 2 3 2 45 0.032 0.00545% 2,263 Release05-009 2 3 3 45 0.032 0.00158% 7,781 Release05-009 2 3 4 90 0.032 0.00339% 7,265 Release05-009 2 3 5 44 0.032 0.00433% 2,783 Release05-009 2 3 6 46 0.032 0.00279% 4,524 Release05-009 2 3 7 48 0.032 0.000273% 48,232 Release05-009 2 3 8 43 0.032 0.000242% 48,780 Release05-009 2 3 9 58 0.032 -0.000177% -89,646 Sorption05-009 2 3 10 47 0.032 0.000269% 47,862 Release 473 05-013 1 4 1 7 39.0 0.0000001% 28,634,635 Release05-013 1 4 2 90 39.0 0.0000000% 894,186,303 Release05-013 1 4 3 90 39.0 0.0000000% 662,189,135 Release 187 05-013 2 4 1 7 39.0 0.0000000% 71,666,636 Release05-013 2 4 2 90 39.0 0.0000001% 289,972,871 Release05-013 2 4 3 90 39.0 0.0000000% 1,513,153,294 Release 187 05-023 1 4 1 7 12.7 0.0000001% 27,020,806 Release05-023 1 4 2 90 12.7 0.0000001% 217,423,321 Release05-023 1 4 3 90 12.7 0.0000001% 222,884,943 Release 187 05-023 2 4 1 7 12.7 0.0000001% 22,251,582 Release05-023 2 4 2 90 12.7 0.0000001% 192,511,093 Release05-023 2 4 3 90 12.7 0.0000002% 127,036,891 Release 187 05-024 1 4 1 7 35.9 0.0000000% 116,137,574 Release05-024 1 4 2 90 35.9 -0.0000001% -320,866,834 Sorption05-024 1 4 3 90 35.9 0.0000000% -736,059,867 Sorption 187 05-024 2 4 1 7 35.9 0.0000000% 97,478,007 Release05-024 2 4 2 90 35.9 -0.0000001% -418,363,021 Sorption05-024 2 4 3 90 35.9 -0.0000001% -460,332,617 Sorption 187 05-025 1 4 1 7 12.6 0.0000000% -71,585,890 Sorption05-025 1 4 2 90 12.6 -0.0000009% -27,276,514 Sorption05-025 1 4 3 90 12.6 -0.0000008% -31,743,484 Sorption 187 05-025 2 4 1 7 12.6 0.0000000% -86,636,216 Sorption05-025 2 4 2 90 12.6 -0.0000009% -26,038,716 Sorption05-025 2 4 3 90 12.6 -0.0000010% -25,362,355 Sorption 187 05-038 1 4 1 7 0.104 0.0000110% 175,125 Release05-038 1 4 2 90 0.104 0.0000155% 1,590,224 Release05-038 1 4 3 90 0.104 0.0000029% 8,600,047 Release 187 05-038 2 4 1 7 0.104 0.0000004% 4,284,755 Release05-038 2 4 2 90 0.104 -0.0000538% -458,675 Sorption05-038 2 4 3 90 0.104 0.0000002% 117,631,310 Release 187 05-040 1 4 1 7 44.5 0.0000000% 592,394,110 Release05-040 1 4 2 90 44.5 0.0000000% -839,331,007 Sorption05-040 1 4 3 90 44.5 0.0000000% 722,511,068 Release 187 05-040 2 4 1 7 44.5 0.0000000% -105,422,344 Sorption

Page 8 of 9
ID No. Replicate Batch

Testing 

Period

No. Days 

in Testing 

Period

Total Hg 

on CCB 

(μg/g)

% Hg on CCB 

Released Over 

Testing Period

Years to Release 100% 

Hg on CCB at Measured 

Rate

Sorption or Release 

over Testing Period

Experiment 

Duration, 

Days

Cum

Sorp

05-040 2 4 2 90 44.5 -0.0000003% -83,152,524 Sorption05-040 2 4 3 90 44.5 -0.0000002% -132,626,936 Sorption 187 06-001 1 4 1 7 64.5 0.0000000% -207,793,209 Sorption06-001 1 4 2 90 64.5 -0.0000001% -188,954,213 Sorption06-001 1 4 3 90 64.5 -0.0000001% -196,211,436 Sorption 187 06-001 2 4 1 7 64.5 0.0000000% -851,189,611 Sorption06-001 2 4 2 90 64.5 -0.0000002% -135,031,899 Sorption06-001 2 4 3 90 64.5 -0.0000002% -164,261,871 Sorption 187 

Page 9 of 9
APPENDIX P 

ELEVATED-TEMPERATURE VAPOR-PHASE 

MERCURY MEASUREMENT FROM COAL 

COMBUSTION BY-PRODUCTS 
ELEVATED-TEMPERATURE VAPOR-PHASE 

MERCURY MEASUREMENT FROM COAL 

COMBUSTION BY-PRODUCTS

Final Report 

AAD Document Control 

U.S. Department of Energy 

National Energy Technology Laboratory 

PO Box 10940, MS 921-143 

Pittsburgh, PA 15236-0940 

Cooperative Agreement No. DE-FC26-02NT41727 

Performance Monitor: Lynn Brickett 

Prepared by: 

David J. Hassett 

Loreal V. Heebink 

Debra F. Pflughoeft-Hassett 

Erick J. Zacher 

Tera D. Buckley 

Energy & Environmental Research Center 

University of North Dakota 

PO Box 9018 

Grand Forks, ND 58202-9018 

2006-EERC-02-05 February 2006
DISCLAIMER

 This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 

 This report is available to the public from the National Technical Information Service, U.S. 

Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders 

accepted at (703) 487-4650. 

ACKNOWLEDGMENT

 This report was prepared with the support of the U.S. Department of Energy (DOE) 

National Energy Technology Laboratory Cooperative Agreement No. DE-FC26-02NT41727 

However, any opinions, findings, conclusions, or recommendations expressed herein are those of 

the authors(s) and do not necessarily reflect the views of DOE. 

EERC DISCLAIMER

 LEGAL NOTICE This research report was prepared by the Energy & Environmental 

Research Center (EERC), an agency of the University of North Dakota, as an account of work 

sponsored by DOE. Because of the research nature of the work performed, neither the EERC nor 

any of its employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement 

or recommendation by the EERC. 

NDIC DISCLAIMER 

 This report was prepared by the Energy & Environmental Research Center (EERC) 

pursuant to an agreement partially funded by the Industrial Commission of North Dakota, and 

neither the EERC nor any of its subcontractors nor the North Dakota Industrial Commission nor 

any person acting on behalf of either: 
(A) Makes any warranty or representation, express or implied, with respect to the 

accuracy, completeness, or usefulness of the information contained in this report, or 

that the use of any information, apparatus, method, or process disclosed in this report 

may not infringe privately owned rights; or 

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the 

use of, any information, apparatus, method, or process disclosed in this report. 

 Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the North Dakota Industrial Commission. The views and 

opinions of authors expressed herein do not necessarily state or reflect those of the North Dakota 

Industrial Commission. 
ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM 

COAL COMBUSTION BY-PRODUCTS 

ABSTRACT 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of (coal combustion by-products 

(CCBs). The EERC is measuring the release of mercury and other air toxic elements under 

different controlled laboratory conditions and investigating the release of these same air toxic 

elements in select field settings. One of the potential release mechanisms under investigation, 

and the subject of this report, is the elevated-temperature vapor-phase release of mercury from 

CCBs. 

 This report includes a summary of the method development and associated results for work 

performed under this project to assess the release of mercury from CCBs when exposed to 

elevated temperatures. The report includes descriptions of the apparatus and method developed. 

It also includes examples of real-time mercury release profiles generated when various fly ash 

and flue gas desulfurization material samples were subjected to temperatures up to 750°C. A 

discussion of work performed using the elevated-temperature releases to speciate mercury on the 

CCBs is presented. The report summarizes the various technical issues associated with 

performing the release experiments and data interpretation. A preliminary interpretation of the 

results generated is included. 
i 

TABLE OF CONTENTS

LIST OF FIGURES ........................................................................................................................ ii 

LIST OF TABLES.........................................................................................................................iii 

EXECUTIVE SUMMARY ........................................................................................................... iv 

INTRODUCTION .......................................................................................................................... 1 

BACKGROUND ............................................................................................................................ 1 

OBJECTIVES................................................................................................................................. 4 

METHODS ..................................................................................................................................... 4 

Mercury Desorption Apparatus and Method......................................................................... 4 

Mercury Speciation Method.................................................................................................. 6 

RESULTS AND DISCUSSION..................................................................................................... 6 

Samples Evaluated for Elevated-Temperature Release......................................................... 6

Elevated-Temperature Release Desorption Curves for Fly Ash ........................................... 7

Elevated-Temperature Release Desorption Curves for FGD Material ............................... 13

Mercury-Spiked Desorption Curves.................................................................................... 13 

CONCLUSIONS........................................................................................................................... 16 

REFERENCES ............................................................................................................................. 16 

LIST OF SAMPLES TESTED WITH MERCURY THERMAL 

DESORPTION APPARATUS ......................................................................................Appendix A 
ii 

LIST OF FIGURES 

1 Mercury desorption curve for an activated carbon sorbent loaded with mercury................. 3 

2 Mercury thermal desorption apparatus.................................................................................. 5 

3 Typical one-peak mercury desorption curve for fly ash........................................................ 9 

4 Typical two-peak mercury desorption curve for fly ash ....................................................... 9 

5 Replicate 1 of a reproducible sample mercury desorption curve, using 

 640.3 mg of sample ............................................................................................................. 10

6 Replicate 2 of a reproducible sample mercury desorption curve, using 

 634.2 mg of sample ............................................................................................................. 10 

7 Replicate 1 of an irreproducible sample mercury desorption curve, using 

 788.9 mg of sample ............................................................................................................. 11 

8 Replicate 2 of an irreproducible sample mercury desorption curve, using 

 581.6 mg of sample ............................................................................................................. 11 

9 Mercury desorption curve for an SDA material generated during injection 

 of activated carbon, using 458.7 mg of sample................................................................... 14 

10 Mercury desorption curve for a baseline (no mercury control) eastern bituminous 

 fly ash, using 855.9 mg of sample....................................................................................... 15 

11 Mercury desorption curve for a baseline (no mercury control) eastern bituminous 

 fly ash spiked with 500 ng of mercuric chloride, using 811.1 mg of sample ..................... 15 
iii 

LIST OF TABLES 

1 Fly Ash Volatilization Results – Hg Concentration.............................................................. 2 

2 Summary of Samples Evaluated in Elevated-Temperature Mercury 

 Release Experiments ............................................................................................................. 6 

3 Summary of Fly Ash Mercury Thermal Desorption Curves Generated to Date................... 7 

4 Breakdown of Number of Peaks Generated for Fly Ash Mercury Thermal 

 Desorption Curves to Date .................................................................................................... 8

5 Summary of FGD Material Mercury Thermal Desorption Curves Generated to Date....... 13 

6 Identified Peak Ranges for FGD Material Mercury Thermal Desorption 

 Curves to Date..................................................................................................................... 13 
iv 

ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM 

COAL COMBUSTION BY-PRODUCTS 

EXECUTIVE SUMMARY 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of coal combustion by-products 

(CCBs). The EERC is measuring the release of mercury and other air toxic elements under 

different controlled laboratory conditions and investigating the release of these same air toxic 

elements in select field settings. One of the potential release mechanisms under investigation, 

and the subject of this report, is the elevated-temperature vapor-phase release of mercury from 

CCBs. 

 Investigation of elevated-temperature mercury release from CCBs at the EERC began in 

1999. The constructed apparatus heated an aliquot of CCB from ambient temperature to 750°C at 

a constant ramp rate. The mercury and mercury compounds desorbed from the CCB were carried 

with nitrogen to a heated analytical quartz cell operated at 800°C to thermally decompose 

compounds to form elemental mercury, which was detected by an atomic absorption 

spectrophotometer. 

 Early work under a DOE task showed that thermal desorption curves generated for 100% 

activated carbon sorbents loaded with mercury indicated a significant level of mercury desorbed 

from the sorbent with reproducible peaks. The curves generated under the early DOE work 

provided background information for this task. 

 A variety of CCBs were evaluated for the real-time elevated-temperature release of 

mercury. The CCBs were primarily fly ash but also included a limited number of flue gas 

desulfurization (FGD) materials. Most samples generated either one or two mercury peaks with a 

range of 0–4 peaks. The temperature of the primary mercury peak for fly ash samples ranged 

from 262° to 750°C, with an average of 468°C. Some samples actually continued to show 

increasing mercury release at 750°C, so the highest peak temperature at which the mercury was 

released could not be determined. More samples collected from mercury emission control tests 

continued to release mercury at 750°C than those collected under conditions without mercury 

emission control testing. 

 The use of elevated-temperature release of mercury was evaluated as a means of 

determining the speciation of mercury present on CCBs. Results indicated that the interaction of 

mercury with the CCBs at elevated temperatures may preclude speciation using this method on 

these complex materials. 

 Thermal desorption curves provided a comparative means of evaluating the 

elevated-temperature release of mercury from a variety of CCBs, but the method and results have 

not yet yielded an understanding of the mechanism of release over the temperature range 

evaluated. 
1 

ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM 

COAL COMBUSTION BY-PRODUCTS

INTRODUCTION 

 The stability of mercury associated with coal combustion by-products (CCBs) has become 

a prominent question as the coal-fired utility industry develops and tests mercury emission 

controls that may consequently increase the mercury associated with CCBs. The reasons for 

evaluating the release of mercury from CCBs are 1) to determine if mercury captured on CCBs is 

stable or if it will be released, thus negating the purpose of the removal of the mercury from the 

emissions, and 2) to aid utilities in determining and understanding changes in CCBs associated 

with mercury control and associated CCB management. 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of CCBs. The EERC is measuring the 

release of mercury and other air toxic elements under different controlled laboratory conditions 

and investigating the release of these same air toxic elements in select field settings. Results will 

be used to determine if mercury released from CCBs, both as currently produced and as 

produced with mercury and other emission controls in place, will impact CCB management 

practices. 

 Laboratory tasks were designed to address three primary potential release mechanisms for 

mercury over the life cycle of CCBs in a variety of management scenarios: 

1. Direct leachability of air toxic constituents from CCBs. 

2. Vapor release of mercury from CCBs at ambient and elevated temperatures. 

3. Biologically mediated leachability and vapor release of mercury and other air toxic 

elements from CCBs. 

 This report focuses on the results generated from measuring mercury release at elevated 

temperatures. Elevated-temperature vapor-phase experiments simulated potential mercury 

release from high-temperature manufacturing processes such as wallboard and cement 

manufacturing. This report is a preliminary summary of elevated-temperature release results for 

the ongoing project entitled “Mercury and Air Toxic Element Impacts of Coal Combustion 

By-Product Disposal and Utilization.” 

BACKGROUND 

 Mercury emission controls will result in reapportioning the mercury that was previously 

released to the atmosphere into CCBs. The stability of mercury associated with CCBs is an issue 

that has only recently been under investigation, but has become a prominent question as the 

industry strives to determine if current management options for CCBs will need to be modified. 
2 

 The release of mercury vapor, both at ambient and elevated temperatures, from CCBs 

resulting from the use of mercury control technologies has been evaluated on a limited basis. 

Samples of CCBs generated under emission control conditions were not readily available until 

DOE initiated field demonstrations of the control technologies. However, some work has been 

accomplished on samples primarily from pilot-scale and short-term tests. Methods of 

determining the release include measuring the mercury in the air, capturing the mercury released 

over extended periods, and evaluating the mercury contents of CCBs at varying periods, which 

generally require very sensitive analytical techniques. 

 Fly ash volatilization studies performed by Schwalb et al. (1) compared total mercury 

contents of several ash samples as received and after exposure to elevated temperatures (100° 

and 140°F [37.7° and 60°C]) for 6 months, with total mercury concentration measured at 3 and 6 

months. Results are shown in Table 1. 

 Limited information has been reported on the stability of mercury captured on sorbents (2). 

Results of thermal desorption tests indicate that mercury is thermally released from sorbents at 

temperatures considerably below the peak temperatures observed for fly ashes. Significant 

percentages of the mercury captured on the saturated sorbents were released upon heating above 

135°C (275°F) in nitrogen, carbon dioxide, or flue gas, and 30%–50% of the original mercury 

capture capacity of the sorbent was regenerated after one or two regeneration cycles. Ambient 

release of mercury into a low flow rate of air was determined by collecting desorbed mercury on 

a sorbent. After correcting for blank determinations, essentially no mercury was released at 

ambient temperature (24°C [75°F]) from either of the sorbents tested. These data may be 

valuable in assessing the potential for rerelease of mercury from spent sorbents. 

 Investigation of elevated-temperature mercury release from CCBs at the EERC began in 

1999. Most of the thermal curves generated were straightforward, containing only one or two 

major desorption peaks (3). 

 In early work performed under a DOE task (4), several samples of 100% activated carbon 

sorbents loaded with mercury were evaluated. Figure 1 shows a desorption curve generated for 

one of these sorbents. The desorption curve indicated that a significant level of mercury was 

 Table 1. Fly Ash Volatilization Results – Hg Concentration, ppm (1) 

3 month 6 month 

Plant ID As-Received 100°F 140°F 100°F 140°F 

3 0.09 ± 0.02 0.09 0.10 0.12 0.17 

6 0.29 ± 0.05 0.34 0.32 0.38 0.34 

6 0.19 ± 0.04 0.22 0.25 0.28 0.24 

6 0.69 ± 0.11 0.72 0.69 0.69 0.69 

4 0.08 ± 0.02 0.11 0.12 0.13 0.12 

4 0.08 ± 0.02 0.09 0.10 0.11 0.13 
3 

Figure 1. Mercury desorption curve for an activated carbon sorbent loaded with mercury. 

desorbed from the sample and, as noted in Figure 1, five peaks were identified. These five peaks 

were reproducible. Other sorbent desorption curves were similar, and it was hypothesized as 

described above that there were multiple binding sites related to several mechanisms of sorption 

or bonding to additives in the carbon sorbents. At the time these curves were generated, the 

calibration of the elevated temperature apparatus had not yet been instituted, so the amount of 

mercury released was not quantitated. 

 No further elevated-temperature experiments were performed on 100% sorbent samples 

under this project, but the curves generated under the early DOE work provided background 

information for this task. 

 Determination of the speciation of mercury present on CCBs has been attempted at the 

EERC (5). Samples were spiked with mercuric oxide (HgO) or mercuric chloride (HgCl2) 

powder. Experimental work was also done on determining the thermal curves for devolatilization 

of HgO and HgCl2 compounds added to pulverized quartz powder to simulate an inert matrix. 

Thermal desorption of HgO produced a sharp, symmetric peak that desorbed at 250°–325°C. The 

peak from HgCl2 desorption was less symmetric and desorbed at temperatures of 200°–250°C. 

When spiking ash samples with HgO and HgCl2, it was found that the complex chemistry and/or 

matrix of the ash sample altered the decomposition of the mercury compounds. All spiked 

samples had peak desorption temperatures higher than that of the spike component alone. In all 

but one sample, the CCBs spiked with HgCl2 eluted peaks at temperatures lower than the plain 

CCB. Spiking samples with HgO yielded variable decomposition temperatures. Unfortunately, 

this delayed desorption was not completely reproducible, making “peak matching” with 

desorption curves of the mercury compounds without ash difficult and problematic. 
4 

 The use of fly ash in cement manufacture has become relatively common in recent years, 

and the use of FGD gypsum in wallboard has grown to the extent that new wallboard plants are 

almost exclusively using FGD and other by-product gypsum. The release of mercury in these 

uses where the CCB is exposed to elevated temperatures has the potential to impact the use 

applications and these industries. Laboratory information will be the starting point to 

understanding the impacts. 

OBJECTIVES 

 The primary objective of the vapor-phase subtask was to evaluate the release of mercury 

from CCBs at ambient, near-ambient, and elevated temperatures to simulate possible mercury 

release in various disposal and utilization scenarios. The elevated-temperature experiments 

simulated high-temperature manufacturing scenarios such as wallboard and cement 

manufacturing. Mercury is more likely to be released at elevated temperatures, and this report 

only focuses on the elevated-temperature release experiments and results. 

 The objective of this report is to report on the method development for and results of 

experiments to evaluate the elevated-temperature vapor-phase release of mercury from CCBs. 

METHODS 

 Mercury Desorption Apparatus and Method 

 Since mercury and mercury compounds are highly volatile, mercury was expected to be 

released from CCBs when they were exposed to elevated temperatures. Even mercury that is 

sorbed on fly ash, flue gas desulfurization (FGD) material, or sorbents developed to remove 

mercury in flue gas is expected to have high potential to be released if exposed to high enough 

temperatures. Instrumental and equipment constraints existed for the physical testing of elevatedtemperature release of mercury from CCBs. These constraints were as follows: 

• Furnaces available for the experimental apparatus could only achieve maximum 

temperatures of 750°C. 

• Fittings and connecting tubing needed to be heated in order to minimize the loss of 

mercury in the system. 

• Gas flow to remove the mercury from the heated sample cell to the analytical cell 

needed to be constant. 

• Temperature ramping needed to be controlled and consistent between sample runs. 

 The apparatus for the investigation of real-time mercury release was constructed as shown 

in Figure 2. The CCB sample was weighed into a quartz tube with quartz wool used to keep the 

sample in place in the tube. Nominal sample size was approximately 1 gram. The sample tube 
5 

was then placed into a small tube furnace capable of achieving a maximum temperature of 

750°C. The furnace was controlled with a temperature controller programmed to ramp the 

furnace from ambient to maximum temperature at a rate of 25°C per minute. In preliminary 

experiments, the maximum temperature achievable was 700°C, but an improved furnace was 

incorporated into the apparatus to increase the maximum achievable temperature to 750°C. A 

nitrogen gas flow of 5 cm3

/min was introduced into the tube furnace. As the mercury and 

mercury compounds desorbed from the CCB in the sample tube, the nitrogen flow carried them 

through the system to the electrically heated quartz analytical cell. The quartz analytical cell was 

operated at 800°C, allowing the detection of mercury compounds by thermally decomposing 

compounds to form elemental mercury, which can be detected by atomic absorption 

spectrophotometer (AAS). The analytical cell was placed in the center-focused beam path of an 

AAS. A mercury hollow cathode lamp was used as the light source, and the AAS detector was 

set to the 253.7-nm line for mercury. A Hewlett Packard 3395 integrator was used for data 

collection. 

 Calibration of the AAS with elemental mercury vapor sorbed onto gold-coated quartz 

produced a peak that was very symmetric and well-defined, decomposing at an average 

temperature of 350°–375°C. Calibration allows quantitation of the amount of mercury desorbed 

from the sample being evaluated. 

Figure 2. Mercury thermal desorption apparatus. 
6 

Mercury Speciation Method 

 It has been hypothesized that the mercury species associated with fly ash, FGD material, or 

carbon can be identified using thermal desorption techniques. EERC researchers performed 

several experiments to confirm or refute this hypothesis. The experimental design focused on the 

use of analytical spikes using mercuric chloride and elemental mercury. CCB samples, quartz 

sand, and quartz powder were all used as a base sample for these evaluations. Mercuric chloride 

was dissolved in ether and then added to the base samples. Elemental mercury was added in a 

gaseous form to CCB samples. The spiked samples were then desorbed using the same apparatus 

and protocol for the mercury release experiments described above. 

RESULTS AND DISCUSSION 

 Samples Evaluated for Elevated-Temperature Release 

 Mercury thermal desorption curves were generated for 39 CCBs, including 18 samples 

without mercury control and 18 samples with mercury control. The sample set included primarily 

fly ash but also included various types of FGD materials. Several sorbents were evaluated under 

earlier EERC work, and data from some of these samples are included for comparison and 

discussion purposes. A list of the samples included in the elevated-temperature release 

experiments is included in Appendix A. Table 2 lists numbers of each sample type based relative 

to coal source and mercury control. It was determined early in the elevated-temperature 

 Table 2. Summary of Samples Evaluated in Elevated-Temperature Mercury 

 Release Experiments

Coal Type Sample Type 

Mercury 

Control 

No. of 

Samples 

Tested 

Total 

Mercury 

Content 

Range, μg/g 

Average 

Total 

Mercury, 

μg/g 

Loss on 

Ignition 

(LOI), % 

Eastern 

 Bituminous 

Fly ash Yes 6 0.4–120 31.8 12.61–23.91 

Eastern 

 Bituminous 

Fly ash No 7 0.01–0.685 0.199 1.07–8.44 

Eastern 

Bituminous 

Fly ash Unknown 3 0.362–1.21 0.730 10.49–10.90 

Lignite Fly ash Yes 7 0.147–2.22 0.857 1.04–4.21 

Lignite Fly ash No 6 <0.01–0.785 0.343 0.34–2.54 

Lignite FGD material Yes 1 0.332 0.332 1.12 

Lignite FGD material No 0 <0.01 <0.01 0.95 

Subbituminous Fly ash Yes 4 0.64–5.5 3.18 2.11–4.14 

Subbituminous Fly ash No 2 0.261–0.578 0.420 0.48–1.08 

Subbituminous FGD material No 1 0.112 0.112 2.07 

Western 

 Bituminous 

Fly ash No 1 0.521 0.521 2.46 
7 

experiments that total mercury content of <0.01 μg/g generally did not allow for a desorption 

curve to be generated with any level of reproducibility. The absolute quantitation limit of the 

apparatus was approximately 10 nanograms. Using a maximum of 1 gram of sample, the 

quantitation limit was used to determine the lower concentration limit of 0.01 μg/g. The bulk of 

the samples evaluated had total mercury content of >0.01 μg/g and, after some preliminary 

attempts to evaluate samples with a lower total mercury content, low mercury samples were 

screened out and not evaluated. 

Elevated-Temperature Release Desorption Curves for Fly Ash 

 As already noted, the release of mercury at elevated temperatures was evaluated by heating 

a sample in a temperature-controlled tube furnace and detecting the emitted mercury or mercury 

compounds with AAS in a t-cell heated to 800°C. Over the duration of the project, the apparatus 

for elevated-temperature release experiments has been modified to increase the achievable 

maximum temperature from 700° to 750°C. During the developmental stages of this apparatus, it 

was also determined that good control of gas flow was essential for good quantitation. Since the 

pressure drop across the sample increases as temperature increases, a mass flow controller was 

added to maintain a constant gas flow. The release of mercury from CCBs at temperatures up to 

750°C is essentially quantitative. Mercury thermal desorption curves were generated throughout 

the project. However, only those generated after the installation of the mass flow controller are 

included in this report to give a better comparison of obtained results. Representative curves are 

shown in Figures 1–8. 

 For this project, most samples desorbed were fly ash samples, and most samples generated 

either one or two mercury peaks with a range of 0–4 peaks. Table 3 summarizes the information 

on the mercury thermal desorption curves by samples with and without mercury control testing. 

The temperature of the primary mercury peak ranged from 262° to 750°C, with an average of 

468°C. Some samples actually continued to show increasing mercury release at 750°C, so the 

highest peak temperature at which the mercury was released could not be determined. More 

samples from mercury control testing continued to release mercury at 750°C 

 Table 3. Summary of Fly Ash Mercury Thermal Desorption Curves Generated to Date

Coal Type Mercury 

Control 

No. of 

Samples 

Tested 

No. of 

Peaks 

Noted 

Range of 

All Peaks, 

°C 

Total Mercury 

Content 

Range, μg/g 

LOI, % 

Eastern 

 Bituminous 

Yes 6 1–4 262–750 0.4–120 12.61–23.91 

Eastern 

 Bituminous 

No 7 0–3 302–750 0.01–0.685 1.07–8.44 

Eastern 

 Bituminous 

Unknown 3 1–2 351–750 0.362–1.21 10.49–10.90 

Lignite Yes 7 1–2 325–632 0.147–2.22 1.04–4.21 

Lignite No 6 0–2 334–750 <0.01–0.785 0.34–2.54 

Subbituminous Yes 4 1–2 318–750 0.64–5.5 2.11–4.14 

Subbituminous No 2 1 333–404 0.261–0.578 0.48–1.08 

Western 

 Bituminous 

No 1 1 330–335 0.521 2.46 
8 

than those without mercury control testing. Although the lowest mercury absorbance peak 

occurred at 262°C for a fly ash sample, some samples showed mercury release beginning before 

250°C. 

 Examples of desorption curves with one and two peaks are shown in Figures 3 and 4, 

respectively. As can be seen in these figures, the single or first peaks tended to rise relatively 

sharply at the initiation of the peak but tailed off with time. In curves where two or more peaks 

were noted, peaks after the initial peak tended to show slightly less definition and were usually 

broader. 

Examples of replicate desorption curves are noted in Figures 5–8. Figures 5 and 6 are 

replicate curves for a sample of lignite fly ash generated during mercury control technology 

testing and show excellent reproducibility. Figures 7 and 8 are replicate curves for a sample of 

eastern bituminous fly ash and show relatively poor reproducibility. While replicates were not 

performed on every sample in the task sample set (Appendix A), where replicates were 

performed, results were generally good. Poor replication generally indicated a highly variable 

sample. 

 Table 4 presents a breakdown of sample reproducibility for replicate mercury thermal 

desorption curves generated for fly ash. Just over half of the samples show a reproducible 

number of peaks generated in replicate runs. However, the remaining samples produced an 

inconsistent number of peaks in replicate runs and are reported as generating a range of peak 

numbers. 

 Table 4. Breakdown of Number of Peaks Generated for Fly Ash Mercury Thermal 

 Desorption Curves to Date 

No. of Samples with Designated No. of 

Peaks 

Coal Type 

Mercury 

Control 

No. of 

Samples 

Tested <DL1

 1 2 3 4 1–2 2–3 1–3 

Eastern 

 Bituminous 

Yes 6 1 1 1 2 1 

Eastern 

 Bituminous 

No 7 1 1 2 1 2 

Eastern 

 Bituminous 

Unknown 3 1 2 

Lignite Yes 7 5 2 

Lignite No 6 1 2 2 

Subbituminous Yes 4 3 1 

Subbituminous No 2 2 

Western 

 Bituminous 

No 1 1 

1

 Detection limit. 
9 

Figure 3. Typical one-peak mercury desorption curve for fly ash. 

Figure 4. Typical two-peak mercury desorption curve for fly ash. 
10 

Figure 5. Replicate 1 of a reproducible sample mercury desorption curve, using 640.3 mg of 

sample. 

Figure 6. Replicate 2 of a reproducible sample mercury desorption curve, using 634.2 mg of 

sample.
11 

Figure 7. Replicate 1 of an irreproducible sample mercury desorption curve, using 788.9 mg of 

sample. 

Figure 8. Replicate 2 of an irreproducible sample mercury desorption curve, using 581.6 mg of 

sample. 
12 

 Samples that have shown the most variability are those that contain activated carbon 

sorbents. The nature of the ash–carbon mixture is to separate, with the carbon moving 

preferentially to the surface of any container in which the sample is stored. The research team 

was aware of this issue, and it was sometimes easily observed in the laboratory handling of the 

samples; however, even very careful mixing and sampling were not adequate to alleviate this 

variability for the small sample size used for thermal desorption experiments. In later thermal 

runs, samples containing no visible carbon showed improved reproducibility after grinding. We 

believe that in these samples the carbon particles may have been coated with ash and, for this 

reason, could not be easily seen. During grinding, the carbon particles became evident as black 

swirls as the material was being ground. The variability of the sample was also readily noted in 

experiments to quantitate mercury releases. In some samples with activated carbon present, 

mercury concentrations determined based on the peaks identified by the integrator (after 

apparatus calibration) were not consistent. This phenomenon was exacerbated as carbon particles 

in the individual samples were noted to be larger. It was determined that this problem could be 

overcome by carefully grinding the samples in a mortar and pestle to allow a more homogeneous 

samples to be placed in the thermal desorption sample tubes. 

 An example of the many problems associated with thermal desorption is a fly ash sample 

containing sulfur-impregnated activated carbon. A sample like this would be expected to produce 

a thermal curve containing more than one peak. The reasons that multiple peaks might occur on a 

thermal desorption profile include the following: 

• Flue gas can contain elemental and oxidized mercury. The oxidized mercury may be 

present as a chloride, oxide, nitrate, or sulfate, and each of these compounds could 

result in a discreet peak on its vaporization. 

• Sorbents may contain other compounds by design as in sulfur- or halogen-impregnated 

activated carbon, which may cause formation of additional mercury compounds, each 

releasing at a discreet temperature. 

 Elemental mercury is known to sorb as an oxidized species on activated carbon. Additives 

such as sulfur or iodine, for example, could lead to the formation of additional compounds such 

as mercuric sulfide or mercuric iodide. During thermal desorption, there are many additional 

things that might happen: 

• Elemental mercury and mercuric chloride can desorb unchanged. 

• Other mercury compounds can decompose into their components as would happen with 

mercuric oxide, which would decompose into oxygen and elemental mercury prior to 

desorption. 

 All of these factors combine in practice to produce thermal desorption curves that, while 

we may not completely understand the process, provide valuable data. 
13 

Elevated-Temperature Release Desorption Curves for FGD Material 

 Some FGD material samples were also subjected to the elevated-temperature protocol. A 

summary of the information on the mercury thermal desorption curves by sample is provided in 

Table 5. Table 6 contains a breakdown of the identified mercury peaks from several sample runs. 

The three samples tested showed a wide variety of mercury release profiles. 

 Figure 9 is an example of a desorption curve for a spray dryer absorber (SDA) material. 

This sample was collected during demonstration of mercury emission control testing using 

activated carbon injection at a lignite-fired power plant. Fly ash is recycled into the SCA system 

at the power plant where these samples were obtained, which is relatively common. 

FGD materials are difficult to analyze with the current elevated-temperature release system 

because of sulfur interferences, moisture, and other possible problems as noted above. 

Mercury-Spiked Desorption Curves 

 Quartz sand and pure quartz powder where spiked with mercuric chloride as an inert 

material similar to CCBs. A single sharp peak was recorded when the mercuric chloride was 

added to the quartz sand. However, when mercuric chloride was spiked onto pure quartz powder, 

a double peak was noted. This suggests that matrix effects may make determination of species 

very unlikely. 

 Table 5. Summary of FGD Material Mercury Thermal Desorption Curves Generated to 

 Date 

Coal Type 

Mercury 

Control 

No. of 

Samples 

Tested 

No. of 

Peaks 

Noted 

Range of 

All Peaks, 

°C 

Total Mercury 

Content, μg/g LOI, % 

Lignite Yes 1 1 312–354 0.332 1.12 

Lignite No 1 0 NA1 <0.01 0.95 

Subbituminous No 1 2–3 270–695 0.112 2.07 

1

 Not applicable. 

 Table 6. Identified Peak Ranges for FGD Material Mercury Thermal Desorption 

 Curves to Date 

Coal Type Mercury Control Identified Peak Ranges No. of Samples Tested 

Lignite Yes 312–354 1 

Lignite No NA 1 

270–280 

430–475 

Subbituminous No 

695 

1 
14 

Figure 9. Mercury desorption curve for an SDA material generated during injection of activated 

carbon, using 458.7 mg of sample. 

 Additional elevated-temperature release experiments were also performed on CCB samples 

spiked with mercury. All samples used in this experiment were fly ash, some of which contained 

activated carbon from mercury emission control demonstrations. The addition of mercuric 

chloride or elemental mercury to the CCBs resulted in a shift of the mercury release peaks noted 

previously from the samples without any added mercury. The peak temperatures measured for 

spiked CCB samples shifted to higher temperatures for some samples and to lower temperatures 

for other samples. 

 Figures 10 and 11 are an example of a fly ash sample tested as described earlier compared 

to a separate aliquot spiked with mercuric chloride. This was done by mixing a single aliquot of 

the CCB, just less than 2 grams, and dividing it into two small, nearly equal portions. One 

portion was left untreated while the other portion was spiked with 50 μL of an ether solution of 

mercuric chloride containing 10 ng/μL of mercuric chloride. This is equivalent to the addition of 

370 ng of mercury as mercuric chloride. Spiking was done in this manner to minimize 

nonhomogeneity between the two aliquots of sample. Mercuric chloride spiking of this fly ash 

sample produced an additional peak to those noted on the original fly ash sample. The reasons 

for an additional peak noted in the spiked sample are the same as why a fly ash sample may 

release multiple peaks of mercury. 
15 

Figure 10. Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly 

ash, using 855.9 mg of sample. 

Figure 11. Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly 

ash spiked with 500 ng of mercuric chloride, using 811.1 mg of sample.
16 

CONCLUSIONS 

 Thermal desorption curves provided a comparative means of evaluating the 

elevated-temperature release of mercury from a variety of CCBs, but the method and results have 

not yet yielded an understanding of the mechanism of release over the temperature range 

evaluated. The possible scenarios for release are as follows: 

• Mercury and mercury compounds, as sorbed, are being released unchanged during the 

thermal desorption procedure. 

• Mercury compounds are being desorbed by a mechanism of thermal decomposition 

whereby sorbed compounds such as HgO are thermally decomposed to mercury and 

oxygen during the thermal desorption. 

• Mercury or mercury compounds are chemically reacting with the CCB components then 

thermally desorbed according to the first or second scenario as described above. 

 The results indicated that the mercury present on CCBs is expected to be released at 

temperatures between 262° and 750°C. In most cases, all the sorbed mercury will be released, 

although some samples did retain some mercury after exposure to 750°C. Some samples showed 

continued release at 750°C so they might not release all their mercury until a higher temperature 

is achieved. While not investigated under this project, the amount of time the CCB is exposed to 

certain temperatures may also impact the amount of mercury released. It is recommended that 

this be investigated, especially for FGD gypsum, which may be exposed to elevated temperatures 

for short times during the preparation for use in wallboard. The use of fly ash that contains 

measurable mercury (with or without sorbent carbon) for cement manufacture has high potential 

to release that mercury based on the results presented. It is recommended that the CCB industry 

work with cement manufacturers to investigate solutions that will facilitate maintenance of this 

market for fly ash. 

REFERENCES 

1. Schwalb, A.M.; Withum, J.A. The Evolution of Mercury from Coal Combustion Materials 

and By-Products. Presented at the Mercury Control Technology R&D Program Review 

Meeting, Pittsburgh, PA, Aug 12–13, 2003. 

2. Carey, T.R.; Richardson, C.F.; Chang, R. Stability of Mercury Captured on Sorbent 

Surfaces. Presented at the Air and Waste Management Association 92nd Annual Meeting 

and Exhibition, St. Louis, MO, June 20–24, 1999. 

3. Laudal, D.L.; Gallagher, J.R.; Hassett, D.J.; Timpe, R.T. Stability of Mercury in Coal 

Combustion By-Products. 2000 Annual Report of the Center for Air Toxic Metals; organized 

and administered through the University of North Dakota Energy & Environmental 

Research Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 

2000; pp 59–68. 
17 

4. Pavlish, J.H. Task 1.2 – Mercury Stability in the Environment; Final Report for U.S. 

Department of Energy National Energy Technology Laboratory, July 1999. 

5. Hassett, D.J.; Heebink, L.V.; Gallagher, J.R.; Laudal, D.L.; Pflughoeft-Hassett, D.F. 

Stability of Mercury in Coal Combustion By-Products and Sorbents. 2003 Annual Report of 

the Center for Air Toxic Metals; organized and administered through the University of North 

Dakota Energy & Environmental Research Center, for U.S. Environmental Protection 

Agency Contract No. R 827649-01; 2003; pp 103–115. 
APPENDIX A

LIST OF SAMPLES TESTED WITH MERCURY 

THERMAL DESORPTION APPARATUS 
A-1 

Table A1. List of Samples Tested with Mercury Thermal Desorption Apparatus 

ID No. Sample Type Coal Type 

Mercury 

Control 

Total Mercury, 

μg/g LOI, % 

02-002 Fly ash Eastern bituminous Yes 30.6 22.17 

02-003 Fly ash Eastern bituminous Yes 21.7 19.38 

02-004 Fly ash Subbituminous Yes 5.5 2.84 

02-005 Fly ash Subbituminous Yes 4.73 4.14 

02-007 Fly ash Eastern bituminous Yes 120 23.91 

02-069 Fly ash Eastern bituminous Yes 0.634 12.61 

02-070 Fly ash Eastern bituminous No 0.193 5.88 

02-072 Fly ash Eastern bituminous No 0.16 5.39 

02-076 Fly ash Eastern bituminous Yes 0.4 21.15 

03-005 Fly ash Eastern bituminous No 0.084 3.60 

03-007 Fly ash Eastern bituminous No 0.141 4.41 

03-011 Fly ash Eastern bituminous Unknown 0.618 10.49 

03-013 Fly ash Eastern bituminous Unknown 0.362 10.90 

03-014 Fly ash Eastern bituminous Unknown 1.21 10.88 

03-016 Fly ash Lignite No 0.016 0.34 

03-018 Fly ash Lignite Yes 0.289 1.17 

03-019 Fly ash Lignite Yes 2.22 4.21 

03-060 Fly ash Subbituminous Yes 1.86 2.47 

03-061 Fly ash Subbituminous No 0.578 1.08 

03-062 Fly ash Lignite Yes 0.49 1.29 

03-078 Fly ash Lignite No 0.662 1.47 

03-079 Fly ash Lignite No 0.785 2.54 

03-088 Fly ash Eastern bituminous No 0.01 1.07 

04-003 Fly ash Eastern bituminous No 0.685 8.44 

04-007 Fly ash Western 

bituminous 

No 0.521 2.46 

04-029 Fly ash Subbituminous No 0.261 0.48 

04-033 Fly ash Lignite Yes 1.43 1.39 

04-035 Fly ash Lignite No 0.159 2.24 

04-036 Fly ash Lignite Yes 0.287 2.16 

04-054 Fly ash Eastern bituminous Yes 17.7 18.60 

04-067 Fly ash Subbituminous Yes 0.64 2.11 

05-001 Fly ash Lignite No <0.01 0.90 

05-002 Fly ash + FGDSDA Lignite No <0.01 0.95 

05-003 Fly ash Lignite Yes 0.565 1.04 

05-004 Fly ash + FGDSDA Lignite Yes 0.332 1.12 

05-005 Fly ash Lignite No 0.431 1.29 

05-017 Fly ash Lignite Yes 0.717 1.70 

05-018 Fly ash Eastern bituminous No 0.123 3.01 

99-188 Fly ash + FGDSDA Subbituminous No 0.112 2.07 
APPENDIX Q 

ELEVATED-TEMPERATURE MERCURY 

RELEASE DATA 
Table Q-1. Elevated-Temperature Mercury Release Results

ID No. Run #

Sample 

Amount (mg)

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

99-188 1154 765.7 270 475 695 FGD-SDA 

99-188 1181 1018.7 280 440 FGD-SDA 99-188 1182 1087.1 275 430 FGD-SDA 02-002 1050 116.1 262 330 411 736 Fly Ash + Activated Carbo02-002 1051 71 278 352 470 740 Fly Ash + Activated Carbo02-003 1052 138.7 290 400 519 750 Peak 1 very small Fly Ash + Activated Carbo02-003 1053 54.4 390 509 748 additional peak evolved after heated at 750° for extended period Fly Ash + Activated Carbo02-004 1054 155.2 318 552 Fly Ash + Activated Carbo02-004 1101 154 334 363 Very close double peak Fly Ash + Activated Carbo

02-004 2879 257 366 start of curve noticed at end of run Fly Ash + Activated Carbo02-005 1056 99.5 326 Fly Ash + Activated Carbo02-005 2880 87.8 358 750 Fly Ash + Activated Carbo02-006 1058 53.9 302 very fine double peak Fly Ash + Activated Carbo02-006 3015 83.4 702 peak tip not very defined Fly Ash + Activated Carbo02-007 1060 19.6 400 518 Fly Ash + Activated Carbo02-007 2877 13.2 433 571 2nd peak is large tailing peak Fly Ash + Activated Carbo02-069 1061 655.2 481 750 high absorbance Fly Ash + Activated Carbo02-069 2921 429.5 474 722 750 Hg release continued when held at 750°C Fly Ash + Activated Carbo02-069 2957 442.4 478 Fly Ash + Activated Carbo02-069 2958 446.8 700 peak was essentially a small bump Fly Ash + Activated Carbo02-069 2959 444.4 750 Fly Ash + Activated Carbo02-069 2960 442 350 685 747 all peaks very small Fly Ash + Activated Carbo02-069 2963 520 410 429 543 705 Fly Ash + Activated Carbo02-069 2965 484.5 415 450 619 739 Fly Ash + Activated Carbo02-069 2966 488.8 445 597 750 Fly Ash + Activated Carbo02-070 1062 707.7 473 741 Fly Ash 02-070 2993 856.4 473 Fly Ash 02-071 1063 541 427 675 Fly Ash + Activated Carbo02-072 1064 792.9 411 558 590 Fly Ash 02-072 2971 770.3 420 645 Fly Ash 02-072 2973 778 612 Fly Ash 02-073 1065 636.3 404 Fly Ash 02-073 2989 912.1 406 524 750 Hg release continued when held at 750°C Fly Ash 

02-074 1068 606.2 399 Fly Ash 02-074 3016 706.2 750 Fly Ash 02-076 1069 710.5 405 750 Hg release continuing at 750°C Fly Ash 02-076 1070 741 417 750 Fly Ash 02-076 2990 709.1 386 602 Fly Ash 02-076 2997 735.3 356 750 Hg release continued when held at 750°C Fly Ash 02-076 2999 722.2 358 708 750 Hg release continued when held at 750°C Fly Ash 02-076 3000 722.5 396 750 Fly Ash 02-076 3006 702.6 365 750 Fly Ash 02-076 3028 363.7 361 750 Fly Ash 03-004 1071 994.7 378 720 Fly Ash 03-004 3014 1070.2 537 Fly Ash 03-005 1072 956.4 384 711 Fly Ash 03-005 1080 530.2 376 750 Hg release continuing at 750°C Fly Ash 03-006 1073 767.7 443 Fly Ash 03-006 2987 894 450 Fly Ash 

Page 1 of 7
ID No. Run #

Sample 

Amount (mg)

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

03-006 2988 884.1 412 575 625 Fly Ash 03-007 1074 788.9 435 740 Fly Ash 03-007 1102 936.2 452 527 718 Fly Ash 03-007 1103 581.6 522 Fly Ash 03-008 1075 942.8 362 Fly Ash 03-016 1082 1001.1 368 Fly Ash 03-016 2904 408.1 354 Fly Ash 03-016 2905 964.8 383 very small bump Fly Ash 03-017 1083 697.1 350 slight peak start at end of run Fly Ash + Activated Carbo03-018 1084 649.2 325 Fly Ash + Activated Carbo03-018 1085 649.3 335 Fly Ash + Activated Carbo03-018 1108 438.1 350 Fly Ash + Activated Carbo03-018 1200 616.4 346 Fly Ash + Activated Carbo03-018 1202 647.6 339 slight increase at end of run Fly Ash + Activated Carbo03-018 2931 638.8 358 Fly Ash + Activated Carbo03-018 2932 639.5 363 Fly Ash + Activated Carbo03-019 1086 221.2 375 Fly Ash + Activated Carbo03-019 1250 186.1 382 Fly Ash + Activated Carbo03-019 1251 167.1 375 Fly Ash + Activated Carbo03-060 1087 197.6 395 Fly Ash + Activated Carbo03-060 1247 202.4 400 Fly Ash + Activated Carbo03-060 1248 196.3 392 Fly Ash + Activated Carbo03-061 1088 556.7 383 Fly Ash 03-061 2908 269.4 404 Fly Ash 03-061 2926 276.9 378 Fly Ash 03-062 1089 629.7 334 Fly Ash + Activated Carbo03-062 1230 595.8 358 Fly Ash + Activated Carbo03-062 1231 596.3 357 sharp peak Fly Ash + Activated Carbo03-062 1239 598.2 346 sharp peak Fly Ash + Activated Carbo03-062 2933 603 398 Fly Ash + Activated Carbo03-062 2934 604.8 368 ground sample Fly Ash + Activated Carbo03-062 2935 602.7 361 Fly Ash + Activated Carbo03-062 2942 606.3 331 Fly Ash + Activated Carbo03-062 2943 604.4 333 jagged peak Fly Ash + Activated Carbo03-062 2945 600 356 Fly Ash + Activated Carbo03-063 1090 990.1 675 no real peak Fly Ash 03-065 1111 1000.9 329 FGD Gypsum 03-078 1044 494.6 350 Fly Ash 03-078 1120 498.4 334 Fly Ash 03-078 1171 505.7 355 jagged top of peak Fly Ash 03-079 1043 236.7 356 Fly Ash 03-079 1121 465.4 361 750 peak not complete at end of run Fly Ash 03-079 2916 506.1 345 Fly Ash 03-080 1122 677.4 380 443 slight increase at end of run Fly Ash 03-080 3018 1105 750 Fly Ash 03-080 3019 1044.7 347 Fly Ash 03-081 1123 641.3 275 346 592 Fly Ash 03-081 2984 479.5 296 750 peak not complete at end of run Fly Ash 03-083 1124 1005.9 413 very broad peak Fly Ash 

03-083 3021 1364.2 358 Fly Ash 

Page 2 of 7
ID No. Run #

Sample 

Amount (mg)

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

03-084 1125 750.1 256 460 720 Fixated FGD 03-085 1126 1003.5 354 748 Fly Ash 03-085 3020 1558.2 392 750 Fly Ash 03-088 1127 1862.8 273 350 551 747 Fly Ash 03-088 1173 1323.1 742 Fly Ash 03-088 1175 1315 487 737 all peaks very small Fly Ash 03-088 1177 1327.8 285 750 all peaks very small Fly Ash 03-089 1128 756.8 298 FGD Gypsum 04-003 1129 467.7 434 Fly Ash 04-003 1178 507.7 393 750 Fly Ash 04-003 1180 504.8 449 Fly Ash 04-003 2918 253 444 Fly Ash 04-004 1130 1606.1 300 Fly Ash 04-006 1131 752.1 378 Fly Ash 04-007 1132 620.5 330 Fly Ash 04-007 2954 626.7 335 Fly Ash 04-029 1133 623.5 352 Fly Ash 04-029 2910 317.3 333 very small peak Fly Ash 

04-030 1143 1308.5 397 750 peak not complete at end of run Fly Ash + Activated Carbo04-030 3013 1011.2 563 Fly Ash + Activated Carbo04-031 3010 890 555 Fly Ash + Activated Carbo04-032 1145 788.2 448 572 747 Fly Ash + Activated Carbo04-032 3009 806.3 318 576 Fly Ash + Activated Carbo04-033 1149 293.5 477 Fly Ash + Activated Carbo04-033 2867 251.4 632 Fly Ash + Activated Carbo04-033 2868 284.9 499 603 Fly Ash + Activated Carbo04-033 2883 251.3 528 Fly Ash + Activated Carbo04-035 1150 715 336 Fly Ash 04-035 1209 558.2 356 Fly Ash 04-035 1215 623.5 362 Fly Ash 04-035 2912 852 370 sample had visible unburned C particles Fly Ash 04-035 2936 768.6 341 jagged peak Fly Ash 04-035 2940 771.2 365 Fly Ash 04-035 2941 769.4 353 jagged peak Fly Ash 04-036 1151 619.7 336

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 1203 640.3 360

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 1204 634.2 368

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 2946 635.2 339

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 2947 632.5 344

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 3022 704.8 324 750

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 3023 885.9 324 ground sample

Fly Ash + Enhancing Agent 

Activated Carbon

04-036 3025 711.8 330

Fly Ash + Enhancing Agent 

Activated Carbon

Page 3 of 7
ID No. Run #

Sample 

Amount (mg)

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

04-054 1153 60.5 385 435 720 Fly Ash + Activated Carbo04-054 1190 99.4 490 Fly Ash + Activated Carbo04-054 1191 115.4 477 Fly Ash + Activated Carbo04-054 1193 104.3 344 500 750 peak not complete at end of run Fly Ash + Activated Carbo04-067 1206 543.9 377 high absorbance

Fly Ash + Enhancing Agent 

Activated Carbon

04-067 1207 482.3 397 high absorbance

Fly Ash + Enhancing Agent 

Activated Carbon

04-067 2884 374.1 433

Fly Ash + Enhancing Agent 

Activated Carbon

04-067 2928 504.1 422 sharp peak

Fly Ash + Enhancing Agent 

Activated Carbon

05-001 1211 532.8 no real peak recorded Fly Ash 05-001 2861 1033.1 289 442 Fly Ash 05-001 2862 1179.5 459 Fly Ash 05-002 1228 453.9 no real peak recorded FGD-SDA 05-003 1223 490.9 335

Fly Ash + Enhancing Agent 

Activated Carbon

05-003 1225 474.8 345

Fly Ash + Enhancing Agent 

Activated Carbon

05-003 1226 496.6 329

Fly Ash + Enhancing Agent 

Activated Carbon

05-003 2890 206.5 385 broad tailing

Fly Ash + Enhancing Agent 

Activated Carbon

05-004 1217 458.7 318 487

FGD-SDA + Enhancing Age

Activated Carbon

05-004 2891 287.8 354

FGD-SDA + Enhancing Age

Activated Carbon

05-004 2953 291.9 312

FGD-SDA + Enhancing Age

Activated Carbon

05-005 1219 405.3 365 Fly Ash 05-005 1220 428.3 377 Fly Ash 05-005 2892 265.2 384 Fly Ash 05-005 2924 520.5 379 all peaks small; sample run through 100-mesh sieve Fly Ash 05-005 3030 778.7 332 sample run through 100-mesh sieve Fly Ash 05-005 3034 729.2 316 sample run through 100-mesh sieve Fly Ash 05-005 3042 673.4 316 sample run through 100-mesh sieve Fly Ash 05-010 2864 782.1 328 393 broad curve with two peaks Fly Ash 05-010 2865 762.9 311 Fly Ash 05-010 3007 777.1 334 750 Fly Ash 05-013 3075 6.2 423 Fly Ash + Activated Carbo05-013 3076 4.8 457 751 Fly Ash + Activated Carbo05-013 3077 5.6 451 526 very jagged Fly Ash + Activated Carbo05-017 2853 341.8 417 578 Fly Ash + Enhancing Agen

05-017 2854 523.5 405 561 Fly Ash + Enhancing Agen05-017 2858 338 403 590 Fly Ash + Enhancing Agen05-017 2863 320.5 406 Fly Ash + Enhancing Agen05-017 3039 485 391 684 Fly Ash + Enhancing Agen05-017 3040 560 399 Fly Ash + Enhancing Agen05-017 3041 403.5 393 666 Fly Ash + Enhancing Agen

Page 4 of 7
ID No. Run #

Sample 

Amount (mg)

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

05-018 2855 788.4 317 747 1st peak high absorbance; Hg release continuing at 750°C Fly Ash 05-018 2857 787.4 340 703 Fly Ash 05-018 2995 822.7 302 564 643 3rd peak on tail of 2nd peak Fly Ash 05-018 3003 855.9 317 581 Fly Ash 05-023 3046 167.2 497 749 high absorbance Fly Ash + Activated Carbo

05-023 3048 55.5 454 746 750 great amount of Hg release after 750°C reached Fly Ash + Activated Carbo

05-023 3050 86.9 471 high absorbance Fly Ash + Activated Carbo

05-023 3053 102.1 471 high absorbance Fly Ash + Activated Carbo

05-023 3054 75.5 469 high absorbance; Hg release continued when held at 750°C Fly Ash + Activated Carbo

05-023 3059 102.1 441 682

Sx in 1008.5 mg quartz sand; high absorbance; Hg release continued when held at 750°C Fly Ash + Activated Carbo

05-023 3062 29 388 Sx in 1002.8 mg quartz sand Fly Ash + Activated Carbo

05-023 3063 32.8 460 586 Hg release continuing at 750°C Fly Ash + Activated Carbo

05-023 3065 19.6 459 577 Fly Ash + Activated Carbo

05-023 3067 13.7 468 Fly Ash + Activated Carbo

05-024 3071 16.2 436 high absorbance Fly Ash + Activated Carbo05-024 3072 9.2 444 Fly Ash + Activated Carbo05-024 3073 8.5 443 Fly Ash + Activated Carbo05-025 3068 31.2 437 Fly Ash + Activated Carbo

05-025 3069 18.6 353 430 704 Fly Ash + Activated Carbo

05-025 3070 20.7 438 684 Fly Ash + Activated Carbo

05-038 3056 941.6 376 697 Hg release continuing at 750°C Fly Ash 05-040 3078 2.9 427 Fly Ash + Activated Carbo05-040 3079 2.2 447 750 Fly Ash + Activated Carbo06-001 3080 1.3 385 Fly Ash + Activated Carbo06-001 3081 1.2 423 Fly Ash + Activated CarboQuartz Sand 3058 1008.5 no peaks Quartz SandQuartz Sand 3084 494 no peaks Quartz SandQuartz Sand 3090 495.8 no peaks Quartz SandQuartz Sand 3108 531.9 no peaks Quartz SandFly Ash Std. 1139 526.9 292 NIST 1633b Fly Ash StandaFly Ash Std. 2951 806.4 450 750 all peaks very small NIST 1633b Fly Ash Standa

Page 5 of 7
Table Q-2. Elevated-Temperature Mercury Release Results for Mercury Spiked Samples

ID No. Run #

Sample 

Amount (mg) Spiked with

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

02-004 1099 155.6 HgCl2 in ether 307 plateau noted half way down tail of peak Fly Ash + Activated Carbon 

02-004 1100 157.5 HgCl2 in ether 307 plateau noted half way down tail of peak Fly Ash + Activated Carbon 02-069 2968 494.7 HgCl2 in ether 306 419 698 750 Hg release continued when held at 750°

C Fly Ash + Activated Carbon 

02-070 2994 778.6 HgCl2 in ether 483 596 Fly Ash 

02-076 2991 713.4 HgCl2 in ether 364 651 Fly Ash 02-076 3001 722 HgCl2 in ether 410 750 Fly Ash 02-076 3002 760.3 HgCl2 in ether 401 Fly Ash 02-076 3027 614.3 HgCl2 in ether 367 Fly Ash 03-007 1104 593.1 HgCl2 in ether 597 Fly Ash 03-007 1105 581.6 Hg0 403 577 1st peak very sharp, 2nd peak broad Fly Ash 

03-007 1106 548.8 Hg0 406 572 1st peak very sharp, 2nd peak broad Fly Ash 03-007 1107 573.9 HgCl2 in ether 431 750 Hg release continued when held at 750°

C Fly Ash 

03-016 2907 458.6 HgCl2 in ether 315 Fly Ash 

03-018 1109 438.8 Hg0 350 Fly Ash + Activated Carbon 

03-018 1110 436.3 HgCl2 in ether 323 Fly Ash + Activated Carbon 

03-061 2909 222.4 HgCl2 in ether 387 broad peak with narrow lip at to

p Fly Ash 

03-061 2927 277 HgCl2 in ether 392 Fly Ash 

03-063 1096 975.2 HgCl2 in ether 307 450 very broad; 2nd peak on tail of 1st peak Fly Ash 

03-063 1097 479.4 HgCl2 in ether 260 tailing peak Fly Ash 03-081 2985 454.2 HgCl2 in ether 320 664 Hg release continued when held at 750°

C Fly Ash 

04-029 2911 331.8 HgCl2 in ether 361 jagged peak Fly Ash 

04-033 2887 105 HgCl2 in ether 331 475 498 all peaks very small Fly Ash + Activated Carbon 04-035 2914 892.5 HgCl2 in ether 351 Fly Ash 

04-036 3024 777.1 HgCl2 in ether 307 750

Fly 

Ash + 

Enhancing 

Agent + 

Activated Carbon

04-036 3026 774.2 HgCl2 in ether 306

Fly 

Ash + 

Enhancing 

Agent + 

Activated Carbon

04-067 2903 393.9 HgCl2 in ether 388

Fly 

Ash + 

Enhancing 

Agent + 

Activated Carbon

04-067 2929 506.7 HgCl2 in ether 407 750

Fly 

Ash + 

Enhancing 

Agent + 

Activated Carbon

05-003 2899 205.7 HgCl2 in ether 370

Fly 

Ash + 

Enhancing 

Agent + 

Activated Carbon

05-004 2900 298 HgCl2 in ether 321

FGD-SDA + 

Enhancing 

Agent + 

Activated Carbon

05-005 2901 271 HgCl2 in ether 376 Fly Ash 

05-005 2923 519 HgCl2 in ether 377 sample run through 100-mesh sieve Fly Ash 

05-010 3008 770.4 HgCl2 in ether 286 382 750 Fly Ash 05-018 2996 885.6 HgCl2 in ether 317 583 Fly Ash 

05-018 3004 811.1 HgCl2 in ether 313 496 569 Fly Ash 

05-038 3055 800 HgCl2 in ether 339 711 Fly Ash 

Blank Tube 2889 1 HgCl2 in ether

Page 6 of 7
ID No. Run #

Sample 

Amount (mg) Spiked with

Peak 1 

(°C)

Peak 2 

(°C)

Peak 3 

(°C)

Peak 4 

(°C) Comments Sample Type 

Blank Tube 2969 1 HgCl2 in ether 408

Blank Tube 2978 1 HgCl2 in ether 287Blank Tube 2979 1 HgCl2 in ether 132 228 very jaggedBlank Tube 2980 1 HgCl2 in ether 203 237 315 very jagged

Quartz 

Powder 1093 513.6 HgCl2 in ether 218 260 Quartz Powder

Quartz 

Powder 1094 501.1 HgCl2 in ether 219 Quartz Powder

Quartz Sand 1092 511.2 HgCl2 in ether 268 Quartz Sand

Quartz Sand 1095 507.2 HgCl2 in ether 264 Quartz SandQuartz Sand 2894 1009.5 HgCl2 in ether 175 218 Quartz SandQuartz Sand 2895 1003.6 HgCl2 in ether 285 Quartz SandQuartz Sand 2896 1014.4 HgCl2 in ether 270 Quartz SandQuartz Sand 3085 492.2 HgCl2 in ether 209 Quartz SandQuartz Sand 3086 460.4 HgCl2 in ether 189 750 Quartz SandQuartz Sand 3087 501.6 HgCl2 in ether 213 240 713 Quartz Sand

Quartz Sand 3089 477.4 HgCl2 in ether 193 236 very jagged Quartz SandQuartz Sand 3091 487 HgCl2 in ether 173 Quartz Sand

Quartz Sand 3092 497.2 HgCl2 in ether 168 202 662 734 very jagged Quartz Sand

Quartz Sand 3093 495.2 HgCl2 in ether 216 Quartz Sand

Quartz Sand 3097 471.1 HgCl2 in ether 191 228 very jagged Quartz Sand

Quartz Sand 3098 488 HgCl2 in ether 200 very jagged Quartz SandQuartz Sand 3101 488.1 HgCl2 in ether 199 Quartz Sand

Quartz Sand 3102 478.6 HgCl2 in ether 207 691 Hg release continued at 750°C Quartz Sand

Quartz Sand 3104 478.8 HgCl2 in ether 199 Quartz Sand

Quartz Sand 3105 482.2 HgCl2 in ether 204 Quartz SandQuartz Sand 3106 470.2 HgCl2 in ether 190 Quartz SandQuartz Sand 3109 489.5 HgCl2 in ether 152 183 Quartz SandQuartz Sand 3110 489.3 HgCl2 in ether 197 Quartz SandQuartz Sand 3111 496.6 HgCl2 in ether 188 Quartz SandQuartz Sand 3112 453.1 HgCl2 in ether 202 Quartz SandQuartz Sand 3113 476.1 HgCl2 in ether 197 Quartz Sand

Page 7 of 7
APPENDIX R 

MICROBIOLOGICALLY MEDIATED MERCURY 

AND AIR TOXIC ELEMENT RERELEASES 

FROM COAL COMBUSTION BY-PRODUCTS 
MICROBIOLOGICALLY MEDIATED MERCURY 

AND AIR TOXIC ELEMENT RERELEASES FROM 

COAL COMBUSTION BY-PRODUCTS

Final Report 

AAD Document Control 

U.S. Department of Energy 

National Energy Technology Laboratory 

PO Box 10940, MS 921-143 

Pittsburgh, PA 15236-0940 

Cooperative Agreement No. DE-FC26-02NT41727 

Performance Monitor: Lynn Brickett 

Prepared by: 

Debra F. Pflughoeft-Hassett 

David J. Hassett 

John R. Gallagher 

Loreal V. Heebink 

Erick J. Zacher 

Rob Jung 

Tera D. Buckley 

Energy & Environmental Research Center 

University of North Dakota 

PO Box 9018 

Grand Forks, ND 58202-9018 

2006-EERC-02-04 February 2006
DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United 

States Government. Neither the United States Government, nor any agency thereof, nor any of 

their employees makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed or represents that its use would not infringe privately owned rights. 

Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States Government or any agency thereof. The views 

and opinions of authors expressed herein do not necessarily state or reflect those of the United 

States Government or any agency thereof. 

This report is available to the public from the National Technical Information Service, U.S. 

Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders 

accepted at (703) 487-4650. 

ACKNOWLEDGMENT

 This report was prepared with the support of the U.S. Department of Energy (DOE) 

National Energy Technology Laboratory Cooperative Agreement No. DE-FC26-02NT41727. 

However, any opinions, findings, conclusions, or recommendations expressed herein are those of 

the authors(s) and do not necessarily reflect the views of DOE. 

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the EERC, an agency of the 

University of North Dakota, as an account of work sponsored by DOE. Because of the research 

nature of the work performed, neither the EERC nor any of its employees makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the accuracy, 

completeness, or usefulness of any information, apparatus, product, or process disclosed, or 

represents that its use would not infringe privately owned rights. Reference herein to any specific 

commercial product, process, or service by trade name, trademark, manufacturer, or otherwise 

does not necessarily constitute or imply its endorsement or recommendation by the EERC. 

NDIC DISCLAIMER 

 This report was prepared by the EERC pursuant to an agreement partially funded by the 

Industrial Commission of North Dakota, and neither the EERC nor any of its subcontractors nor 

the North Dakota Industrial Commission nor any person acting on behalf of either: 

(A) Makes any warranty or representation, express or implied, with respect to the 

accuracy, completeness, or usefulness of the information contained in this report, or 
that the use of any information, apparatus, method, or process disclosed in this report 

may not infringe privately owned rights; or 

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the 

use of, any information, apparatus, method, or process disclosed in this report. 

 Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the North Dakota Industrial Commission. The views and 

opinions of authors expressed herein do not necessarily state or reflect those of the North Dakota 

Industrial Commission. 
MICROBIOLOGICALLY MEDIATED MERCURY AND AIR TOXIC ELEMENT 

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS 

ABSTRACT 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of coal combustion by-products 

(CCBs). The EERC is measuring the release of mercury and other air toxic elements under 

different controlled laboratory conditions and investigating the release of these same air toxic 

elements in select field settings. One of the potential release mechanisms under investigation, 

and the subject of this report, is the biologically mediated leachability and vapor release of 

mercury and other air toxic elements from CCBs. 

 This report includes a summary of the method development over the course of this project 

and the associated results. It also summarizes the various technical issues associated with 

performing the release experiments and the analyses of the mercury released in both the vapor 

and liquid phases. A preliminary interpretation of the results generated is also included, but a 

final data analysis and interpretation will be included in the final report for the ongoing project. 
i 

TABLE OF CONTENTS

LIST OF FIGURES ........................................................................................................................ ii 

LIST OF TABLES.........................................................................................................................iii 

EXECUTIVE SUMMARY ........................................................................................................... iv 

INTRODUCTION .......................................................................................................................... 1 

BACKGROUND ............................................................................................................................ 2 

OBJECTIVES................................................................................................................................. 3 

METHODS ..................................................................................................................................... 3 

Description of Initial Apparatus and Method........................................................................ 4 

Modifications of the Apparatus and Experimental Design ................................................... 5 

CCB Preparation Methods .................................................................................................... 5 

Microbiological Innoculum Growth Conditions and Media................................................. 6 

Experimental Incubation Conditions..................................................................................... 6 

Mercury Analyses ................................................................................................................. 8 

Microbiological Analysis ...................................................................................................... 8

RESULTS AND DISCUSSION..................................................................................................... 9 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 1 .................... 9 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 2 .................. 10 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 3 .................. 11 

Microbiologically Mediated Release of Mercury and Air Toxic 

 Elements from CCBs – Experiment 4 ................................................................................. 12 

Microbiologically Mediated Release of Mercury and Air Toxic 

 Elements from CCBs – Experiment 5 ................................................................................. 15 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 6 .................. 18 

OBSERVATIONS AND CONCLUSIONS ................................................................................. 19 

REFERENCES ............................................................................................................................. 20 

MICROBIOLOGICAL SAMPLE SET .........................................................................Appendix A 
ii 

LIST OF FIGURES 

1 Early microbiologically mediated mercury vapor-phase collection 

 apparatus utilizing a wrist action shaker to facilitate mixing................................................ 4 

2 Current microbiologically mediated mercury vapor-phase collection 

 apparatus utilizing a stir plate to facilitate mixing ................................................................ 6 

3 Summary of microbiological results ................................................................................... 18 
iii 

LIST OF TABLES 

1 Microbiological Rerelease Apparatus Modifications............................................................ 5 

2 Experimental Incubation Conditions..................................................................................... 7 

3 CCB Sample Description and Total Mercury Content, Experiment 1.................................. 9 

4 Results of Microbiologically Released Mercury from Sample 99-188, Experiment 1....... 10 

5 CCB Sample Description and Total Mercury Content, Experiment 2................................ 11 

6 Results of Microbiologically Released Mercury from Sample 01-002, Experiment 2....... 11 

7 CCB Sample Description and Total Mercury Content, Experiment 3................................ 12 

8 Results of Microbiologically Mediated Release of Vapor-Phase 

 Mercury and Total Bacterial Counts for Sample 03-060, Experiment 3 ............................ 12 

9 CCB Sample Description and Total Mercury Content, Experiment 4................................ 13 

10 Initial Elemental Mercury Release, Experiment 4 .............................................................. 13 

11 Results Including Eh, pH, and Ending Sample Description, Experiment 4........................ 14 

12 Vapor-Phase Mercury Release Results, Experiment 4........................................................ 15 

13 Solution Organomercury Results, Experiment 4................................................................. 16 

14 Leached Total Trace Element Results, Experiment 4 ......................................................... 16 

15 Samples Included in Microbiological Release Experiment 5 ............................................. 16 

16 Microbiological Eh and pH Results, Experiment 5............................................................. 17 

17 Vapor-Phase Mercury Release Results, Experiment 5........................................................ 17 

18 Microbiological Leached Total Trace Element Results...................................................... 18 

19 Microbiological Buffer Total Trace Element Results ......................................................... 18 

20 Samples Included in Microbiological Release Experiment 6 ............................................. 19 
iv 

MICROBIOLOGICALLY MEDIATED MERCURY AND AIR TOXIC ELEMENT 

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS 

EXECUTIVE SUMMARY 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of coal combustion by-products 

(CCBs). The EERC is measuring the release of mercury and other air toxic elements under 

different controlled laboratory conditions and investigating the release of these same air toxic 

elements in select field settings. One of the potential release mechanisms under investigation, 

and the subject of this report, is the biologically mediated leachability and vapor release of 

mercury and other air toxic elements from CCBs. 

 The EERC’s method to evaluate the mercury release potential from CCBs by leaching and 

offgassing under microbiologically mediated conditions has undergone several modifications 

since it was first developed in 1999. The current apparatus uses a 9-place stir plate to facilitate 

mixing of the CCB, a buffer, and microbes. An improved buffer uses 100 ppm of phosphate and 

potassium glutamate as the nitrogen source. Early experiments with starved microbes did not 

promote microbial growth; therefore, all samples in later experiments were fed with glucose. An 

innoculum from a local brackish wetland added to 10 mL of 0.9% NaCl and vortexed was 

introduced to the samples. Sulfuric acid was added to neutralize alkaline samples prior to 

introducing the microbes. The sample mixtures were allowed to incubate in sealed flasks at room 

temperature for 4 weeks. Experiments were all performed in triplicate. 

 Several methods were used to collect, measure, and speciate the mercury release from 

CCBs. Vapor-phase organomercury compounds were trapped on Supelco CarbotrapTM collection 

traps, with the remaining mercury collected on gold-coated quartz collection traps. The 

CarbotrapTM collection traps were analyzed for total mercury by heating the trap to 

approximately 300°C, passing the released organomercury through a tube at about 800°C, and 

collecting the mercury vapor on a gold-coated quartz trap. All gold-coated quartz traps were 

desorbed for analysis by heating to approximately 500°C and determining the mass of mercury 

released with atomic fluorescence (AF). Total mercury concentrations of the leachate were 

determined using cold-vapor atomic fluorescence spectroscopy (CVAFS). Solid-phase 

microextraction (SPME) was used to determine organomercury species of the mercury present in 

leachates. The air toxic element—arsenic, cadmium, chromium, lead, nickel, and selenium—

concentrations of the leachate were determined by inductively coupled plasma (ICP) and ICP–

mass spectrometry (ICP–MS). 

 A variety of CCB samples were evaluated for microbiologically mediated mercury releases 

using the methods described. Aerobic and anaerobic glucose-fed conditions were used in the 

experiments on fly ash and wet limestone flue gas desulfurization (FGD) filter cake material. 

The fly ash samples evaluated were from eastern bituminous, subbituminous, and lignite coalfired power plants, with total mercury contents ranging from 0.004–1.86 μg/g. The FGD material 
v 

had a 0.218-μg/g mercury content and a significant natural population of sulfate-reducing 

bacteria. Data collected to date are variable, and work will continue on the experimental release 

method and the analytical methods. 
1 

MICROBIOLOGICALLY MEDIATED MERCURY AND AIR TOXIC ELEMENT 

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS

INTRODUCTION 

 The stability of mercury associated with coal combustion by-products (CCBs) has become 

a prominent question as the coal-fired utility industry develops and tests mercury emission 

controls that may consequently increase the mercury associated with CCBs. The reasons for 

evaluating the release of mercury from CCBs are 1) to determine if mercury captured on CCBs is 

stable or if it will be released, thus negating the purpose of the removal of the mercury from the 

emissions, and 2) to aid utilities in determining and understanding changes in CCBs associated 

with mercury control and associated CCB management. 

 Under an effort funded by the U.S. Department of Energy (DOE) and industry entitled 

“Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and 

Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of 

mercury and other air toxic elements on the management of CCBs. The EERC is measuring the 

release of mercury and other air toxic elements under different controlled laboratory conditions 

and investigating the release of these same air toxic elements in select field settings. Results will 

be used to determine if mercury released from CCBs, both as currently produced and as 

produced with mercury and other emission controls in place, will impact CCB management 

practices. 

 Laboratory tasks were designed to address three primary potential release mechanisms for 

mercury over the life cycle of CCBs in a variety of management scenarios. These release 

mechanisms are: 

1. Direct leachability of air toxic constituents from CCBs. 

2. Vapor release of mercury from CCBs at ambient and elevated temperatures. 

3. Biologically mediated leachability and vapor release of mercury and other air toxic 

elements from CCBs. 

 This report focuses on the methods development for and results generated from 

microbiologically mediated experiments to measure rerelease of mercury from CCBs. This report 

includes a summary of the methods development over the course of this project and the 

associated results. It also summarizes the various technical issues associated with performing the 

release experiments and the analyses of the mercury released in both the vapor and liquid phases. 

A preliminary interpretation of the results generated is also included, but final data analysis and 

interpretation will be included in the final report for the ongoing project entitled “Mercury and 

Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization” Under 

which this work was performed. 
2 

BACKGROUND 

 A majority of mercury emission controls currently being developed and demonstrated in 

the United States are expected to result in reapportioning of mercury that was previously released 

to the atmosphere into CCBs. Research on CCBs has not previously focused on mercury, 

primarily because the levels of mercury were low and difficult to quantitate, but the potential for 

significantly increased levels of mercury to be present on CCBs, especially fly ash and FGD, has 

raised the question of its potential to be rereleased from the CCBs under standard management 

scenarios. This question should have been addressed prior to implementing mercury emission 

controls at coal-fired power plants because rerelease or emission from the CCBs could 

potentially negate the use of the mercury emission controls. Preliminary work in the area of 

direct leaching and direct vapor-phase rerelease of mercury from CCBs indicated that these 

releases were expected to be very low (1–5). However, the investigation of the microbiologically 

mediated rerelease of mercury from CCBs had only been initiated on a preliminary level when 

this project was developed (2–4). Since the chemistry of mercury is unique in that it can form 

extremely toxic organomercury compounds when exposed to a variety of microorganisms, the 

rerelease of mercury from CCBs exposed to microbes, including filamentous fungi, is of great 

interest both from the fundamental chemistry standpoint and from the CCB management 

standpoint. 

 There is a wide distribution and variety of microorganisms in the environment that can 

promote the rerelease of mercury from many sources including CCBs, and many of these 

microorganisms have been found to be present in CCB disposal sites and certainly are present in 

environments where CCBs may be used such as in combination with soils for various use 

applications. A wide variety of specific microbe interactions can affect key elements associated 

with CCBs, including oxidation/reduction and alkylation/dealkylation reactions. Additionally, in 

order for microbes to be metabolically active, a few constraints must be satisfied. These include 

a food source, water, and an appropriate pH. For some CCBs and in some CCB management 

scenarios, these criteria are unlikely to be met, but for scenarios where they can be met, 

laboratory experiments can be used to simulate appropriate scenarios. Designing these 

experiments is a challenge as reported previously by the EERC (2–4, 6). The experiments needed 

to address a variety of materials and take into consideration the microbiological processes that 

are expected to allow mercury to be rereleased from CCBs. 

 Microbiological processes that can affect mercury associated with CCBs are: 

• Methylation–demethylation type reactions involving sulfate-reducing bacteria. 

• Formation of: 

– Methylmercuric chloride. 

– Dimethyl mercury. 

– Ethylmercuric chloride. 

– Diethyl mercury. 

– Many possible others. 
3 

OBJECTIVES 

 The overall goal of the project under which this work was accomplished is to support 

continued environmentally responsible management of CCBs and appropriate federal regulation 

of CCBs. Results will provide an indication of appropriate utilization guidelines and disposal 

requirements. If the environmental performance of CCBs from conventional and advanced 

emission control systems is similar, it will facilitate the maintenance of current CCB markets and 

minimize the potential for an additional barrier to utilization of CCBs. If the environmental 

performance changes, the proposed project will facilitate an understanding of appropriate 

management options and provide direction for any future regulatory assessment of CCBs. 

Supporting objectives of the project are to 1) determine the release potential of selected air toxic 

elements, including mercury and other air toxic elements, from CCBs under specific 

environmental conditions; 2) increase the database of information on mercury and other air toxic 

element releases for CCBs; 3) develop comparative laboratory and field data; and 4) develop 

appropriate laboratory and field protocols. 

 The objective of this report is to provide information on the methods development for and 

results of experiments to evaluate the microbiologically mediated rerelease of mercury, arsenic, 

cadmium, chromium, lead, nickel, and selenium from CCBs. Primary work was accomplished on 

release of mercury. 

METHODS 

 Early work at the EERC resulted in development of a preliminary method to determine 

vapor-phase rerelease of mercury from CCBs under microbiologically mediated conditions. 

Development of the method took into consideration the properties of CCBs, the chemistry of 

mercury, and the microbiological processes that could occur under CCB disposal or land 

application. The methodology, developed at the EERC, required the CCB or CCB–soil mixture 

to be buffered to near neutral with phosphate buffer. The sample was dosed with glucose as a 

carbon and energy source and salts to stimulate microbial growth and inoculated with a source of 

microbes. The inoculated sample is sparged with mercury-free gas (either air or argon) and 

monitored for the release of elements from the mixture. 

 In the EERC review of published data on the release of mercury from CCBs (1), it was 

reported that the method developed by the EERC was the only published method developed and 

demonstrated for use in evaluating the release of mercury from CCBs on exposure to natural 

biota. The EERC method has been under development since approximately 1999 and has 

undergone numerous modifications to achieve the goal of evaluating the mercury release 

potential by leaching and offgassing when CCBs are under microbiologically mediated 

conditions. The first experiments performed using early versions of the apparatus focused on 

mercury releases by offgassing. Over the duration of this project, it was decided that the 

apparatus and experiments could also be used to determine if microbiologically mediated 

leaching of mercury was occurring, and measurement of organomercury compounds and air 

toxic elements in leachate was included as part of the methods development and analysis. 
4 

Description of Initial Apparatus and Method 

 The first apparatus assembled to conduct microbiologically mediated vapor-phase mercury 

release used a 250-mL Erlenmeyer flask fitted with an impinger inlet/outlet tube with the inlet 

center shortened to 6 cm below the standard taper. Cylinder gas was passed through several sets 

of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas 

distribution manifold that routed the gas through 0.25-mm gas chromatography (GC) capillary 

tubing to each of the individual flasks. A GC capillary length of approximately 60 cm, when 

pressurized to between 1 and 2 psig through a gas distribution manifold, provided a convenient 

means of regulating gas flow to approximately 2 cm3

/min. The gas passed mercury vapor from 

the head space of the flasks to a mercury vapor collection system at the outlet of the flasks, 

consisting of two traps. A gold-coated quartz trap (for collection of elemental mercury) and a 

Supelco CarbotrapTM (for collection of organomercury compounds) were used to collect mercury 

released in the vapor phase from the flasks. 

 The flasks were placed on a 16-flask wrist action shaker. The experimental matrix 

consisted of eight flasks under anaerobic conditions (using argon) and eight flasks under aerobic 

conditions (using breathing-quality air). In each set of eight flasks, two contained only buffer, 

three contained the CCB with buffer (starved), and three contained the CCB with buffer and 

glucose (fed). A 50-gram aliquot of CCB was placed in the flasks, and ~100 mL of a phosphate 

buffer (with or without glucose, as appropriate) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bacterial culture added. The source of bacteria was a 

mixed bacterial inoculum from a brackish wetland. This setup is illustrated in Figure 1. 

Figure 1. Early microbiologically mediated mercury vapor-phase collection apparatus utilizing a 

wrist action shaker to facilitate mixing. 
5 

Modifications of the Apparatus and Experimental Design 

 The apparatus as described underwent several iterations as difficulties were identified and 

solutions developed. The wrist-action shaker was abandoned, as it was inadequate to suspend the 

sample during the experiments. Instead of the wrist action shaker, samples were placed in 

Erlenmeyer flasks on a 9-place stir plate. This was operated for about 20 minutes every 3 hours 

to maintain sample agitation over the 30-day experiment period. Additionally, the sample size 

was reduced to 20 grams and the buffer increased to 135–150 mL to provide adequate sample 

volume for additional trace element analyses. The buffer composition was also altered. It was 

found that phosphate and nitrate interfered with a derivitization step in the determination of 

organomercury compounds in the solid-phase microextraction (SPME) process using gas 

chromatographic separation followed by detection of the mercury compounds by atomic 

fluorescence. This technique is described later. The original buffer utilized nominal 

concentrations of phosphate and nitrate salts. The improved buffer used only 100 ppm of 

phosphate and substituted potassium glutamate as the nitrogen source. This simple change 

appeared to remove the interferences. Additionally, later experiments did not involve the use of 

starved control samples. In current experiments, all samples are fed with glucose. Table 1 

summarizes the modifications and indicates the experimental difficulties that the modifications 

were employed to correct or improve. The final experimental apparatus used for the majority of 

the project microbiological experiments is illustrated in Figure 2. 

CCB Preparation Methods 

 Some CCBs, especially fly ash, can be alkaline in nature. CCB alkalinity can be attributed 

to the dissolution of alkaline metal oxides that react with water to generate net alkalinity. Watersoluble calcium content contributes most of a CCB’s net alkalinity. This trend can be seen in the 

classification of fly ashes; Class C fly ash is enriched in Ca and Mg and subsequently generates 

pH values considerably higher than Class F fly ash (e.g., pH >10). 

Table 1. Microbiological Rerelease Apparatus Modifications 

Original Experiment or Apparatus 

 Component Difficulty or Unmet Need 

Modified Experiment or 

Apparatus Component 

Wrist Action Shaker, 

 Continuous Shaking 

Inadequate suspension of sample. Magnetic stir plate, 

 intermittent stirring. 

50–80-gram Sample Size + 

 ~100-mL Buffer 

Inadequate volume of liquid to 

 recover for leachate analysis. 

~20 gram sample + 135– 

 150 mL buffer. 

Phosphate Nitrate Buffer Solution Interference with the determination of 

 the organomercury compounds in 

 leachate. 

Lower concentration of 

 phosphate with potassium 

 glutamate as nitrogen 

 source. 

Glucose-Fed and Starved 

 Experiments 

Starved experiments did not promote 

 microbial growth so were deemed 

 unnecessary. 

All experiments fed with 

 glucose. 

Gold-Coated Quartz Trap Was 

 Followed by Carbotrap at Gas 

 Exit (only in Experiment 1) 

Organomercury was trapped on the 

gold-coated quartz so organomercury 

could note be measured. 

Carbotrap was followed by 

 gold-coated quartz trap at 

 gas exit. 
6 

Figure 2. Current microbiologically mediated mercury vapor-phase collection apparatus utilizing 

a stir plate to facilitate mixing. 

 In order for a CCB, or any material, to support biological activity, it must be near neutral 

pH. Microbiological activity of sulfate-reducing bacteria is viable only in the pH range of 6.5 to 

8.5, requiring substantial neutralization of some CCBs. Prior to initiation of experiments, the 

buffer for that experiment was added to individual samples, pH of the ash–buffer mixture was 

measured, and an appropriate volume of acid was added over a period of time to achieve a 

neutral pH. 

Microbiological Innoculum Growth Conditions and Media 

 Since the microbes that promote the release of mercury are ubiquitous, freshly collected 

sediment from a local brackish wetland was used as the innoculum. This innoculum contained a 

variety of microbes including both aerobic and anaerobic bacteria and, therefore, was identified 

as an appropriate innoculum. The source of the innoculum was the same for all experiments. 

 The innoculum was prepared by using 1 gram of sediment taken approximately 2 mm from 

the surface of the sample so that is was more likely that a high concentration of anaerobic 

organisms would be present. This sample was added to 10 mL of 0.9 % NaCl and vortexed. This 

suspension was then used to inoculate the CCB slurry samples. 

Experimental Incubation Conditions 

 Samples were allowed to incubate in sealed flasks at room temperature for 4 weeks. 

Experiments were all performed in triplicate. Table 2 provides information on the incubation 

conditions for microbiological rerelease experiments performed under this project. 
7 

Table 2. Experimental Incubation Conditions

Experiment 

Number of 

Samples Run 

in Triplicate 

Apparatus 

Used Acid Addition Buffer 

Ash-to-Buffer 

Ratio In

Experiment 1 1 Original 

apparatus 

 Phosphate/nitrate buffer 50 g to 94 mL Anae

 with  starv

Experiment 2 1 Original 

apparatus 

 Phosphate/nitrate buffer 50 g to 100 mL Anae

 with  starv

Experiment 3 1 Original 

apparatus 

Phosphoric acid  added to neutralize  solution pH to  allow microbial  growth 

Phosphate/nitrate buffer 80 g to 100 mL Anae

 with  starv

Experiment 4 3 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth 

Phosphate/glutamic acid  buffer 

20 g to 150 mL Anae

 gluc

Experiment 5 3 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth for  fly ash samples 

Phosphate/glutamic acid  buffer 

20 g to 150 mL Anae

 gluc bact flue  (FG

Experiment 6 4 Modified 

apparatus 

Sulfuric acid added to  neutralize solution  pH to allow  microbial growth 

Phosphate/glutamic acid  buffer 

18 g to 135 mL Anae

 gluc
8 

Mercury Analyses 

 The mercury collected in the traps designed to collect mercury released in the vapor phase 

was quantitated at the conclusion of each experiment. The gold-coated quartz collection traps 

were desorbed for analysis by heating to approximately 500°C, and the mass of mercury released 

was determined using atomic fluorescence (AF) yielding a result indicating the elemental 

mercury vapor-phase release. The CarbotrapTM collection traps were analyzed for total mercury 

by heating the trap to approximately 300°C, passing the released organomercury through a tube 

at about 800°C, and collecting the mercury vapor on a gold-coated quartz trap, which was 

analyzed as described above. The result from this analysis was reported as vapor-phase 

organomercury released. 

 The leachate was separated from the sample in order to determine the concentrations of 

mercury in solution. Total mercury concentrations of the leachate were determined using 

CVAFS (cold-vapor atomic florescence spectroscopy). 

 In order to determine organomercury species of the mercury present in the leachates, 

SPME was used. SPME is a sample collection technique utilizing a fiber coated with 

polydimethylsiloxane. Samples containing organomercury compounds are first derivatized to 

increase the volatility of organomercury halides such as methylmercuric chloride. The 

derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and 

sodium tetraphenyl borate. Sodium tetraethyl borate was most commonly used. In the 

derivitization procedure, derivatizing agent, acetate buffer, an internal standard (usually propyl 

mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, 

the halide is replaced with the appropriate alkyl or aryl group, depending on which derivatizing 

agent is chosen. A SPME fiber was inserted through the septum cap, and the sample was stirred 

using a Teflon-coated stir bar for 20 minutes. After this equilibration time, the SPME fiber was 

introduced into the heated inlet zone of a GC. Sample separation can be accomplished using a 

0.53-mm capillary column 15 or 30 meters in length. The exit end of the column was connected 

to a heated quartz tube (800°C), and makeup helium gas was added to increase the total flow to 

between 25 and 30 mL per minute. The gas was then routed to an AF detector for determination 

of the separated mercury compounds. 

Five mL of the liquid plus an aliquot of ethylmercuric chloride as an internal standard was 

placed into a 15-mL septum-capped nonactinic vial containing a Teflon-coated stir bar. 500 μL 

of a pH 4.5 acetate buffer was added followed by 200 μL of a 1% solution of sodium 

tetrapropylborate. SPME sampling was accomplished using a 100-μm polydimethylsiloxanecoated fiber and sampler from Supelco (Bellefonte, Pennsylvania). The head space was sampled 

for 20 minutes after which the SPME fiber was directly introduced into the GC. 

Microbiological Analysis 

 Bacterial counts were performed upon completion of the experiments to determine if there 

were adequate active microbes present at the completion of the experiment to account for any 

mercury releases found. A 1-mL aliquot of solution was taken from each flask. The aqueous 

supernate was serially diluted in 0.1% sodium pyrophosphate buffer (pH 7) and then used to 
9 

inoculate a series of tubes containing 1% PTYG (peptone, tryptone, yeast extract, glucose) broth. 

The tubes were incubated at 25°C, and growth, as turbidity, was monitored over a 3-week period. 

 Of the 18 samples, half were grown under anaerobic conditions and the other half were 

grown under aerobic conditions. Ash samples were removed from the shaker table and a 1-mL 

aliquot was removed for further processing. 

 Prior to processing, the ash sample was stored in a flask at 4°C. When processing, 100 μL 

was removed and added to 9.9 mL sodium pyrophosphate (PP) buffer (0.1% w/v) pH 7.0 with 

three glass beads in each test tube. This was vortexed for 30 s then serially diluted into PP buffer 

(up to 1/1000 dilution). These dilutions were used to inoculate a 3-tube most probable number 

(MPN) assay with 1% peptone–tryptone–yeast extract–glucose (PTYG) buffer. 4 mL of PTYG 

were placed in each 13 × 100-mm tube along with innoculum and incubated at room 

temperature. Tubes and plates (peptone–yeast extract–glucose [PYG] agar) inoculated with 

samples from the anaerobic ash suspension were incubated under anaerobic conditions 

(anaerobic hood), and aerobic ash suspension samples were exposed to atmospheric oxygen. At 

week intervals, they were scored based on turbidity. 

RESULTS AND DISCUSSION 

 A variety of CCB samples were evaluated for microbiologically mediated mercury releases 

using the methods described. The results of experiments are presented for each experiment so the 

results can be discussed relative to the methods modifications that were required over the course 

of the project. Samples included primarily coal combustion fly ash. A complete summary of the 

samples evaluated and identifying information is included in Appendix A. 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 1 

 The first microbiologically mediated mercury release experiment was performed on one 

CCB buffered to near neutral with a phosphate–nitrate buffer. The CCB tested in Experiment 1 is 

listed in Table 3. The sample was dosed with glucose as a carbon and energy source and salts to 

stimulate microbial growth and inoculated with a source of microbes. The inoculated sample was 

sparged with mercury-free gas and monitored for the release of mercury from the mixture. 

Mercury vapor-phase releases only were quantitated from Experiment 1. 

 The results from the experiment using Sample 99-188, a subbituminous fly ash neutralized 

prior to the experiment, are shown in Table 4. AF instrument problems resulted in incomplete 

results for the elemental mercury captured on some of the gold-coated quartz traps because of the 

 Table 3. CCB Sample Description and Total Mercury Content, Experiment 1

Sample Sample Type Coal Type 

Mercury 

Control 

Additional 

Information 

Total 

Mercury, μg/g

99-188 Fly ash + FGDSDA Subbituminous No Neutralized 0.131 
10 

Table 4. Results of Microbiologically Released Mercury from Sample 99-188, Experiment 1

Anaerobic 

Gold Trap Hg, 

pg 

Gold Trap Hg, 

pg/g/day 

CarbotrapTM Hg, 

pg 

CarbotrapTM Hg, 

pg/g/day 

Blank 3920 NAa 300 NA 

Blank 3980 NA 190 NA 

Fed 63,100 43.5 720 0.50 

Fed 45,600b 31.5b 2320 1.60 

Fed 69,200 47.7 4140c

 2.86c

Starved NTd NT 1830 1.26 

Starved 47,700b

 32.9b 5620 3.88 

Starved 66,300 45.7 2070 1.43 

Aerobic 

Blank 23,700 NA 80 NA 

Blank 16,500 NA 60 NA 

Fed 31,500 1090 1060 36.5 

Fed 61,300 2110 860 29.5 

Fed 33,200 1140 1930 66.4 

Starved 45,000 1550 660 22.8 

Starved 42,200 1460 500 17.3 

Starved 44,900 1550 890 30.8 

a

 Not applicable. 

b

 Low value because of analyzing conditions. 

c

 High value because of analyzing conditions. 

d

 Not tested. 

unexpected high masses of mercury. The elemental mercury release results appear to be higher 

from the anaerobic condition. No trend is apparent for the organomercury results. This may be 

because the order of the gold-coated quartz and CarbotrapTM collection traps was incorrect. The 

gold-coated quartz traps were placed nearest the flask outlet during the experimentation; 

therefore, it is believed that some of the organomercury was trapped on the gold-coated quartz 

traps before the gas passed to the CarbotrapTM collection traps. The bacterial count showed more 

bacteria in the flasks in which the bacteria were fed glucose in both the anaerobic and aerobic 

conditions. 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 2 

 The second microbiologically mediated mercury release experiment was performed the 

same as Experiment 1, using Sample 01-002, described in Table 5. 
11 

 Table 5. CCB Sample Description and Total Mercury Content, Experiment 2 

Sample Sample Type Coal Type 

Mercury 

Control 

Total 

Mercury, μg/g

01-002 Fly ash Eastern bituminous No 0.234 

 The results from the experiment using Sample 01-002, an eastern bituminous fly ash, are 

shown in Table 6. The blank flasks, containing only buffer, yielded higher mercury release 

values than those containing the CCB slurry. The mercury release results show that more 

elemental mercury was released from flasks in which the bacteria were fed with glucose versus 

starved. These values are much lower than those from Sample 99-188, pg/g/day versus ng/g/day. 

The bacterial count results show that the bacteria were able to survive in the aerobic environment 

and that within the aerobic environment, the bacterial count was higher at the end of the 

experiment in the flasks where the bacteria were fed with glucose. 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 3 

 The third microbiologically mediated mercury release experiment was performed similarly 

to Experiments 1 and 2. However, phosphoric acid was added to the flasks to neutralize the 

slurry pH. The sample tested is shown in Table 7. 

Table 6. Results of Microbiologically Released Mercury from Sample 01-002, Experiment 2 

Anaerobic Gold Trap Hg, pg 

Gold Trap Hg, 

pg/g/day 

CarbotrapTM Hg, 

pg 

CarbotrapTM Hg, 

pg/g/day 

Blank 1280 NAa 95.47 NA 

Blank 2303 NA 203 NA 

Fed 155 0.0968 13.45 0.00840 

Fed 177.3 0.111 14.12 0.00882 

Fed 376.9 0.236 12.66 0.00791 

Starved 66.49 0.0415 13.16 0.00822 

Starved 45d

 0.0281 22.29 0.0139 

Starved 56.28 0.0352 19.9 0.0124 

Aerobic 

Blank 1096 NA 36.16 NA 

Blank 1160 NA 44.52 NA 

Fed 405.71 0.253 13.76 0.00860 

Fed 1758 1.10 52d

 0.0325 

Fed 136.1 0.0851 13.16 0.00822 

Starved 48d

 0.0300 5.876 0.00367 

Starved 79.39 0.0496 13.59 0.00849 

Starved 30.48 0.0190 4.739 0.00296 
12 

 Table 7. CCB Sample Description and Total Mercury Content, Experiment 3 

Sample Sample Type Coal Type Mercury Control Total Mercury, μg/g 

03-060 Fly ash Subbituminous Yes 1.86 

 Results from CCB 03-060, a subbituminous fly ash collected during a mercury control test, 

are shown in Table 8. These results show that elemental mercury is being released from the 

CCB-containing flasks in the aerobic environment in which the bacteria are fed with glucose. 

The mass of mercury released from the blank flasks in the aerobic environment was much lower 

than in the anaerobic environment. 

 The results of Experiments 1–3 (Tables 4, 6, and 8) showed some general trends. The 

mercury released from the CCB slurry was generally higher in the samples fed with glucose 

versus starved samples and in aerobic versus anaerobic conditions. The bacterial count followed 

a similar trend. The flasks containing buffer only were used as blanks. 

Microbiologically Mediated Release of Mercury and Air Toxic Elements from 

CCBs – Experiment 4 

 Three samples (see Table 9) were evaluated under aerobic and anaerobic glucose-fed 

conditions in triplicate. A 20-gram sample, 150-mL buffer solution, a sample-dependent amount 

of sulfuric acid, and a 100-μL aliquot of a sulfate-reducing bacteria culture were used for 

evaluation. The bacteria were added 4 days after the addition of the buffer and acid to allow the 

systems to neutralize. The system was stirred intermittently over the duration of the experiment. 

Vapor-phase organomercury released from the system was captured in tubes containing Supelco 

CarbotrapTM, and elemental mercury releases were captured on gold-coated quartz traps. 

 Three days after the bacteria was introduced to the experimental vessels, Sample 03-082 

under anaerobic conditions exhibited notable changes. The CCB changed from a cream to a gray 

color, and a hydrogen sulfide smell was emanating from the flasks. The gas from these flasks 

was directed to flasks containing zinc acetate to capture the hydrogen sulfide being produced. 

Table 8. Results of Microbiologically Mediated Release of Vapor-Phase Mercury and Total 

Bacterial Counts for Sample 03-060, Experiment 3

Anaerobic Aerobic 

Condition 

Elemental 

Mercury, 

pg/g/day 

Organomercury, 

pg/g/day Condition 

Elemental 

Mercury, 

pg/g/day 

Organomercury, 

pg/g/day 

Fed 0.069 0.008 Fed 1.7 0.010 

Fed 0.092 0.007 Fed 0.65 0.018 

Fed 0.033 0.002 Fed 1.3 0.007 

Starved 0.025 0.001 Starved 0.024 0.003 

Starved 0.021 0.001 Starved 0.020 0.002 

Starved 0.049 0.002 Starved 0.038 0.002 
13 

Table 9. CCB Sample Description and Total Mercury Content, Experiment 4 

ID No. Sample Type Coal Type Mercury Control Total Mercury, μg/g 

03-079 Fly ash Lignite No 0.785 

03-082 FGD 

filtercake 

Eastern 

bituminous 

No 0.218 

04-043 Fly ash Lignite No 0.689 

Fifteen days after the addition of bacteria, crystal-like formations were noted on the liquid 

surface layer from Sample 04-043, two flasks under anaerobic and one under aerobic conditions. 

 In this experiment, 3 weeks elapsed before the addition of the buffer solution; therefore, 

the gold-coated quartz traps were analyzed to determine the amount of initial elemental mercury 

released from the samples in the interim period (see Table 10). Sample and blank flasks 

generally released similarly low quantities of mercury, but Sample 03-082 under aerobic 

conditions released significantly more elemental mercury than the other samples. This wet FGD 

sample was determined to contain a significant population of sulfate-reducing bacteria. The now 

mercury-free gold-coated quartz traps were then replaced on the flasks for collection of 

elemental mercury over the duration of the experiment. 

 Upon completion of the experiment, evaluations included pH, Eh, elemental and 

organomercury vapor releases, solution organomercury content, and solution elemental 

concentrations. 

 A description of the contents of each sample flask upon completion of the experiment is 

included in Table 11. After the liquid was filtered from the solid, the pH and Eh values were 

determined. For Samples 03-079 and 03-082, the pH was higher under anaerobic conditions than 

aerobic; the opposite was true for Sample 04-043. A greater amount of mold was noted in the 

Sample 04-043 aerobic flasks that yielded a higher pH. 

 Table 10. Initial Elemental Mercury Release, pg/g/day, Experiment 4 

Anaerobic Aerobic 

ID No. Initial Elemental ID No. Initial Elemental 

03-079 0.0534 03-079 0.0732 

03-079 0.0417 03-079 0.0622 

03-079 0.0358 03-079 0.0204 

03-082 0.264 03-082 9.20 

03-082 0.0341 03-082 9.29 

03-082 0.178 03-082 9.83 

04-043 0.0454 04-043 0.0313 

04-043 0.0245 04-043 0.0356 

04-043 0.0358 04-043 0.0588 

a One flask broke; therefore, only two samples were evaluated.
14 

Table 11. Results Including Eh, pH, and Ending Sample Description, Experiment 4 

Anaerobic Aerobic 

ID No. Eh, mV pH Sample Description ID No. 

Eh, 

mV pH Sample Description 

03-079 164 8.23 Black layer on top 

of clear liquid; 

liquid bubbles; 

brown ash 

03-079 374 8.09 Very slightly brown 

liquid; black and brown 

coatings on flask; dark 

brown ash 

03-079 179 8.30 Black layer on top 

of clear liquid; 

liquid bubbles; 

brown ash 

03-079 314 8.02 Film on top of liquid; 

very slightly brown 

liquid; black and brown 

coatings on flask; dark 

brown ash 

03-079 189 8.45 Black layer on top 

of clear liquid; 

liquid bubbles; 

brown ash 

03-079 354 7.97 Two spots of mold; 

film on top of liquid; 

very slightly brown 

liquid; black and brown 

coatings on flask; dark 

brown ash 

03-082 !176 8.39 Gray liquid and 

ash; H2S smell; 

crusted bubbles on 

top of liquid—

round on top and 

broken on bottom 

03-082 a a a

03-082 !161 8.55 Gray liquid and 

ash; H2S smell; 

slightly crusted 

bubbles on top of 

liquid 

03-082 39 7.89 Slightly gray liquid 

with gold crust on top; 

smelled like baby 

formula; gray ash 

03-082 !146 8.51 Gray liquid and 

ash; H2S smell; 

slimy on top of 

liquid 

03-082 44 7.92 Slightly yellow liquid; 

smelled like baby 

formula; gray ash 

04-043 164 6.85 Some carbon 

particles on top of 

clear liquid; no 

noticeable smell; 

grayish-brown ash 

04-043 354 7.61 Layer of mold on top of 

slightly gray liquid 

confirmed by smell; 

grayish-brown ash 

04-043 154 6.95 Some carbon 

particles on top of 

clear liquid; no 

noticeable smell; 

grayish-brown ash 

04-043 279 7.15 No mold smell; grayish 

liquid; carbon granules 

on top of liquid; 

grayish-brown ash 

04-043 149 6.81 Some carbon 

particles on top of 

clear liquid; no 

noticeable smell; 

grayish-brown ash 

04-043 134 7.36 Patch of mold on top of 

gray liquid; grayishbrown ash 

a

 One flask broke; therefore, only two samples were evaluated.
15 

 The results from the three samples evaluated under the modified method are shown in 

Table 12 and reported as picograms of mercury per grams of CCB. In some instances, the results 

were highly variable for the replicate flasks. The highest release of both elemental and 

organomercury was from Sample 03-082 under aerobic conditions. Analysis of the gold-coated 

quartz traps from Sample 03-082 under anaerobic conditions resulted in a white, sulfur-smelling 

deposit on the gold trap. Analyzing the CarbotrapTM tubes from Sample 03-082 aerobic condition 

caused a sulfur smell to be released with no deposit formed. Analyzing the CarbotrapTM tubes 

from Sample 03-082 anaerobic condition resulted in a noticeable sulfur-smelling smoke to be 

released, and a subsequent formation of a white- to yellow-colored deposit on both the 

CarbotrapTM and pyrolysis tube. The amount of vapor-phase elemental mercury released 

coincided with the amount of mold present in the Sample 04-043 aerobic flasks at the completion 

of the experiment. 

 SPME was used to determine organomercury compounds in the liquid remaining in the 

flasks after the experimental collection period. Results are shown in Table 13. 

 Solution elemental concentrations are shown in Table 14. 

Microbiologically Mediated Release of Mercury and Air Toxic Elements from 

CCBs – Experiment 5

 Three samples (Table 15) were evaluated in aerobic and anaerobic glucose-fed conditions 

in triplicate. A 20-g sample, a 150-mL buffer solution, a sample-dependent amount of sulfuric 

acid, and a 100-μL aliquot of a sulfate-reducing bacteria culture were used for evaluation. The 

experimental systems were brought to a neutral pH by addition of the buffer solution and sulfuric 

acid. The bacteria were added after neutral pH conditions were found to be stable. The remainder 

of the protocol and setup were the same as in Experiment 4 for Samples 04-035 and 04-036. 

Samples 04-035 and 04-036 were a paired sample set, collected before and during mercury 

emission control testing, respectively. Sample 03-082, a moist FGD sample evaluated in 

 Table 12. Vapor-Phase Mercury Release Results, Experiment 4

Anaerobic Aerobic 

ID No. 

Elemental 

Mercury, 

pg/g 

Organomercury, 

pg/g ID No. 

Elemental 

Mercury, 

pg/g 

Organomercury, 

pg/g 

03-079 4.1 5.7 03-079 14.7 9.1 

03-079 2.8 5.0 03-079 11.3 30.8 

03-079 5.3 6.7 03-079 19.8 2.5 

03-082 12.7 41.3 03-082 a a

03-082 0.7 2.6 03-082 486 90.0 

03-082 1.5 102 03-082 648 110 

04-043 1.3 1.1 04-043 46.5 4.5 

04-043 2.2 0.6 04-043 4.0 1.4 

04-043 1.9 1.0 04-043 9.1 1.3 

a

 One flask broke; therefore, only two samples were evaluated.
16 

 Table 13. Solution Organomercury Results, Experiment 4

Anaerobic Aerobic 

ID No. 

Methylmercury 

Measured, 

pg/mL 

Methylmercury 

Released, 

pg/g/day ID No. 

Methylmercury 

Measured, 

pg/mL 

Methylmercury 

Released, 

pg/g/day 

03-079 13 2.65 03-079 32 6.67 

03-079 15 3.05 03-079 7 1.47 

03-079 <5 <1 03-079 12 2.50 

03-082 a a 03-082 b b

03-082 250 50.7 03-082 18 3.75 

03-082 a a 03-082 99 20.6 

04-043 31 6.30 04-043 <5 <1 

04-043 19 3.86 04-043 65 13.6 

04-043 18 3.65 04-043 13 2.72 

a

 Samples precipitated colloidal sulfur on standing and were not analyzed. 

b One flask broke; therefore, only two samples were evaluated. 

 Table 14. Leached Total Trace Element Results, μg/L, Experiment 4

Anaerobic Aerobic 

ID No. As Cd Cr Pb Hg Ni Se ID No. As Cd Cr Pb Hg Ni Se

03-079 99 15 10 <2.0 0.15 350 200 03-079 76 16 2.0 <2.0 <0.01 24 48

03-079 95 15 9.6 <2.0 <0.01 330 200 03-079 49 17 <2.0 <2.0 0.095 36 37

03-079 87 16 8.8 <2.0 <0.01 320 190 03-079 56 17 2.0 <2.0 <0.01 27 14

03-082 12 <0.2 7.7 <2.0 a 25 16 03-082 b b b b b b b

03-082 14 <0.2 20 <2.0 a 25 9.9 03-082 17 <0.2 37 <2.0 0.024 33 17

03-082 11 <0.2 6.8 <2.0 a 27 8.5 03-082 28 <0.2 11 <2.0 0.070 31 20

04-043 12 5.5 8.0 <2.0 <0.01 260 79 04-043 140 5.9 7.1 <2.0 0.020 140 190

04-043 11 5.2 7.8 <2.0 <0.01 250 79 04-043 90 4.2 3.8 <2.0 4.9 130 170

04-043 11 4.7 7.7 <2.0 <0.01 250 78 04-043 71 3.4 3.8 <2.0 0.013 100 210

a

 Samples precipitated colloidal sulfur on standing and were not analyzed. 

b

 One flask broke; therefore, only two samples were evaluated.

 Table 15. Samples Included in Microbiological Release Experiment 5

ID No. Sample Type Coal Type Mercury Control Total Hg, μg/g 

03-082 FGD filtercake Eastern bituminous No 0.218 

04-035 Fly ash Lignite No 0.160 

04-036 Fly ash Lignite Yes 0.287 

Experiment 4, required minor revisions to the protocol. The amount of sample was increased 

from 20 to 22 g to account for the moisture present, and no acid or bacteria were added to this 

sample. Sulfate-reducing bacteria were found to be present in the sample as received, and this 

experiment was designed to take advantage of these natural conditions to serve as a comparison 

to the experiment run previously under the standard protocol. 
17 

 Upon completion of the experiment, evaluations included pH, Eh, elemental and 

organomercury vapor releases, solution mercury and trace element concentrations, and a 

bacterial count. 

 Vapor-phase elemental and organomercury releases were determined using the method 

described earlier. 

 Sample 03-082 under anaerobic conditions changed from a cream color to gray and began 

to release hydrogen sulfide within 5 days of buffer addition. As noted previously, this sample 

was not inoculated and had no acid addition. In the previous experiment, this sample was 

inoculated 4 days after buffer and acid addition, with hydrogen sulfide release 3 days after 

inoculation. Therefore, it appears that the pH of Sample 03-082 with the buffer addition and the 

natural bacteria in the sample is sufficient to produce hydrogen sulfide. 

 The results for Experiment 5 are shown in Tables 16–19. A summary of microbiological 

results for the anaerobic and aerobic experiments is noted in Figure 3. 

 Table 16. Microbiological Eh and pH Results, Experiment 5

Anaerobic Aerobic 

ID No. Eh, mV pH ID No. Eh, mV pH 

03-082 −10 8.52 03-082 92 7.81 

03-082 −94 8.52 03-082 81 7.83 

03-082 105 8.41 03-082 86 7.83 

04-035 −11 11.26 04-035 12 10.56 

04-035 −21 11.17 04-035 10 10.39 

04-035 −13 11.20 04-035 −10 10.53 

04-036 −8 11.29 04-036 −25 10.74 

04-036 −14 11.14 04-036 −3 10.68 

04-036 −12 11.25 04-036 −18 10.53 

Table 17. Vapor-Phase Mercury Release Results, pg/g/day, Experiment 5

Anaerobic Aerobic 

ID No. Elemental Mercury Organomercury ID No. Elemental Mercury Organomercury

03-082 NT* NT 03-082 4.64 0.935 

03-082 1.54 NT 03-082 9.69 1.62 

03-082 NT NT 03-082 8.98 1.01 

04-035 0.0279 0.0364 04-035 0.190 0.113 

04-035 0.0366 0.0251 04-035 0.150 0.0876 

04-035 0.0317 0.135 04-035 0.202 0.0153 

04-036 0.0352 0.0242 04-036 0.449 0.0482 

04-036 0.147 0.0815 04-036 0.265 0.111 

04-036 0.516 0.139 04-036 0.374 0.0723 

* Not tested. 
18 

Table 18. Microbiological Leached Total Trace Element Results, μg/L 

Anaerobic Aerobic 

ID No. As Cd Cr Pb Hg Ni Se ID No. As Cd Cr Pb Hg Ni Se

03-082 56 0.36 15 <2.0 0.034 22 23 03-082 14 0.35 13 <2.0 0.018 28 26

03-082 7.9 0.32 14 <2.0 0.041 16 3.8 03-082 19 0.35 15 <2.0 0.014 39 34

03-082 96 0.31 16 <2.0 0.036 18 22 03-082 26 0.34 13 <2.0 0.037 22 30

04-035 NT* NT NT NT NT NT NT 04-035 NT NT NT NT NT NT NT

04-036 NT NT NT NT NT NT NT 04-036 NT NT NT NT NT NT NT

* Not tested. 

 Table 19. Microbiological Buffer Total Trace Element Results, μg/L

Element As Cd Cr Pb Hg Ni Se 

Concentration <2.0 0.41 18 <2.0 <0.01 <2.0 <2.0 

Anaerobic 

Samples 04-035 and 04-036 exhibited no growth in either the broth or plates. Sample 03-082 

did show growth in PTYG broth. A bright yellow color to the media in the test tubes 

indicated the presence of sulfur-reducing bacteria, especially one flask of Sample 03-082. 

Cell density was not determined in this sample, and the plates for this sample’s dilution 

exhibited no growth. 

Aerobic 

Samples 04-035 and 04-036 exhibited no growth on either broth or plates. 

Sample 03-082 plate counts indicated cell density in excess of 25 million cells per mL in the 

original sample. When the MPN was performed on the dilution samples in PTYG broth, they 

indicated cell densities in agreement with the plate counts. 

Figure 3. Summary of microbiological results. 

 It is likely that for the samples (04-035 and 04-036) that did not exhibit growth, it was due 

largely to pH fluctuations occurring during the fly ash slurry portion of the experiment. Results 

of leachate mercury and air toxic element concentrations are found in Table 18. The leachate 

from Samples 04-035 and 04-036 was not tested because of the excessive pH levels. The 

microbiological buffer was tested for the same elements (Table 19). Mercury mobilization can be 

correlated with growth of microorganisms. 

Microbiologically Mediated Release of Mercury from CCBs – Experiment 6 

 A sixth experiment was initiated to evaluate four samples (Table 20) under aerobic and 

anaerobic glucose-fed conditions in triplicate. The latest method was modified slightly. An 18-g 

(instead of 20-g) sample, a 135-mL (instead of 150-mL) buffer solution, and a 100-μL aliquot of 

a sulfate-reducing bacteria culture were used for evaluation. The sample and buffer aliquots were 
19 

 Table 20. Samples Included in Microbiological Release Experiment 6

ID No. Coal Type Sample Type Mercury Control Total Hg, μg/g 

04-035 Lignite Fly ash No 0.160 

04-036 Lignite Fly ash Yes 0.287 

05-001 Lignite Fly ash No 0.004 

05-003 Lignite Fly ash Yes 0.565 

reduced to allow for more sulfuric acid, but the ratio of sample to buffer solution was 

maintained. A sample-dependent amount of sulfuric acid was added over an extended period of 

time instead of within 1 day. The bacteria were added after the addition of the buffer and acid to 

allow the systems to neutralize. The system was stirred intermittently over the duration of the 

experiment. 

 The samples evaluated consisted of two paired sample sets, collected before and during 

mercury control testing. Samples 04-035 and 04-036 were repeated from the previous 

experiment because the pH had risen above the acceptable pH range for bacterial survival by the 

end of the previous experiment. 

 Acid addition over an extended period was attempted to maintain an acceptable pH level 

over the duration of the last 30-day experiment. However, the pH of an aerobic sample measured 

10.5 at the 20-day mark, which was significantly above the acceptable range of 6.5–8.5 for 

bacterial survival. The pH of all samples exceeded 10.5, which killed the bacteria. A pH 

adjustment of all samples was attempted for reinoculation of bacteria but was unsuccessful, and 

this experiment was aborted because the samples could not be pH-adjusted to an appropriate 

range to support microbial activity. 

OBSERVATIONS AND CONCLUSIONS 

 As noted throughout this report, the laboratory development of the method used and its 

application to a variety of samples offered significant challenges. Major challenges were: 

• High blank values from the buffer solutions. 

• Generation of hydrogen sulfide from high-sulfur samples, resulting in poisoning of the 

analytical traps. 

• Difficulty in maintaining a neutral pH, and associated microbial growth, in samples 

with an initially high pH. 

• Growth of fungi in addition to bacterial growth in some samples. 

• Difficulty in maintaining constant gas flow to a large number of sample containers, 

which was solved by use of GC capillary tubing. 

• Difficulty in keeping samples suspended. 

 Several general conclusions can be drawn from the work presented in this report. 
20 

 The formation of organomercury compounds was evident in all of the microbiologically 

mediated experiments. Unexpectedly, the greatest releases were found under aerobic conditions. 

This has been tentatively related to fungal action but has not yet been verified. It has been 

observed, however, that organomercury formation appears to be directly related to the amount of 

fungi present in the flasks at the end of the experiments. It had been expected that 

sulfate-reducing bacteria, known to be present in our innoculum and in FGD material samples, 

would be the primary source of methylation. 

 Sulfate-reducing bacteria in sulfur-rich samples such as FGD material tended to form large 

amounts of hydrogen sulfide in the anaerobic flasks. This hydrogen sulfide production required 

putting traps on the flasks in order to keep the hydrogen sulfide and its odor out of the lab. The 

hydrogen sulfide also made analyses impossible because of the formation of colloidal sulfur soon 

after the samples were harvested. Additionally, hydrogen sulfide collected in the CarbotrapTM 

tubes, came off as elemental sulfur and precluded analyses of these traps in our normal manner. 

This analytical problem is under investigation, but no solution has yet been developed. 

 A further modification to our protocol will involve using a distillation step in the 

determination of organomercury in aqueous samples. This will eliminate matrix effects in the 

derivitization step used just prior to analysis by gas chromatography. 

 Highly alkaline ash samples generated from lignite have proven particularly difficult to 

maintain at near neutrality. Experiments performed in the absence of bacteria provide us with a 

neutralization capacity for acid addition, but in microbiological experiments, these neutralized 

solutions quickly rise to above pH 10.5, thus killing the bacteria. We have been using dilute 

sulfuric acid for neutralization and believe that after neutralization, a sulfate coating has 

deposited around individual particles. After bacteria are introduced, we believe that the bacterial 

action may be removing the protective sulfate coating from alkaline particles thus releasing 

additional alkalinity. At this time, this is our only working hypothesis and solutions based on this 

hypothesis are under investigation. 

REFERENCES 

1. Energy & Environmental Research Center. Mercury Information Clearinghouse. Quarter 4 – 

Rerelease of Mercury from Coal Combustion By-Products, Oct 2004. 

2. Laudal, D.L.; Hassett, D.J.; Heebink, L.V.; Gallagher, J.R. Stability of Mercury in Coal 

Combustion By-Products. 2001 Annual Report of the Center for Air Toxic Metals; organized 

and administered through the University of North Dakota Energy & Environmental 

Research Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 

2001; pp 51–60. 

3. Hassett, D.J.; Heebink, L.V.; Gallagher, J.R.; Pflughoeft-Hassett, D.F.; Laudal, D.L. 

Stability of Mercury in Coal Combustion By-Products and Sorbents. 2002 Annual Report of 

the Center for Air Toxic Metals; organized and administered through the University of North 
21 

Dakota Energy & Environmental Research Center, for U.S. Environmental Protection 

Agency Contract No. R 827649-01; 2002; pp 69–76. 

4. Hassett, D.J.; Heebink, L.V.; Gallagher, J.R.; Laudal, D.L.; Pflughoeft-Hassett, D.F. 

Stability of Mercury in Coal Combustion By-Products and Sorbents. 2003 Annual Report of 

the Center for Air Toxic Metals; organized and administered through the University of North 

Dakota Energy & Environmental Research Center, for U.S. Environmental Protection 

Agency Contract No. R 827649-01; 2003; pp 103–115. 

5. Heebink, L.V.; Hassett, D.J.; Release of Mercury Vapor from Coal Combustion Ash. J. Air 

Waste Manage. 2002, 52 (8), 927–930. 

6. Heebink, L.V.; Pflughoeft-Hassett, D.F.; Hassett, D.J.; Zacher, E.J.; Eylands, K.E. Mercury 

and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization. 

2004 Annual Report of the Center for Air Toxic Metals; organized and administered through 

the University of North Dakota Energy & Environmental Research Center, for U.S. 

Environmental Protection Agency Contract No. R 827649-01; 2004; pp 115–131. 
APPENDIX A

MICROBIOLOGICAL SAMPLE SET 
A-1 

pH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.

ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total Total Trace SGLP 30-day LTL 60-day LTL Thermal Curve Long-Term A

99-188 Fly ash + FGD–SDA Subbituminous No 0.112 12.34 2.07% Completed Completed Completed Completed Completed Underway Complete01-002 Fly ash Eastern bituminous No 0.187 4.03 6.05% Completed Complet03-060 Fly ash Subbituminous Yes 1.86 11.32 2.28% Completed Completed Completed Completed Completed Underway Complete03-079 Fly ash Lignite No 0.785 11.72 2.54% Completed Completed Completed Completed Completed Underway IS 03-082 FGD filtercake Eastern bituminous No 0.218 7.47 4.20% Completed Completed Completed Completed Completed Pending Underwa04-035 Fly ash Lignite No 0.159 12.68 2.24% Completed Completed Completed Completed Completed Completed Underwa

04-036 Fly ash Lignite Yes 0.287 12.64 2.16% Completed Completed Completed Completed Completed Completed Underwa04-043 Fly ash Lignite No 0.689 11.48 Pending Completed Pending Pending Pending Pending Pending IS 05-001 Fly ash Lignite No < 0.005 12.84 0.90% Completed Completed Underway Pending Pending Underway Pending 

05-003 Fly ash Lignite Yes 0.565 12.85 1.04% Completed Completed Underway Pending Pending Underway Pending 
APPENDIX S 

MICROBIOLOGICALLY MEDIATED LEACHING 

AND VAPOR-PHASE TRANSPORT TASK 

SAMPLE SET 
ID No. Sample Type Hg Control Configuration Coal Type Hg (μg/g)

10–15-Min 

pH, Avg. 24-Hr pH

99-188 FGD-SDA PRB Subbituminous 0.112 12.38 12.22 01-002 Fly Ash Eastern Bituminous 0.187 3.90 NT 03-006 Fly Ash Eastern Bituminous 0.194 4.71 6.78 03-007 Fly Ash Eastern Bituminous 0.141 4.27 5.52 03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.86 11.32 11.90 03-079 Fly Ash Fort Union Lignite 0.785 11.77 11.62 03-082 FGD Filtercake Eastern Bituminous 0.233 7.83 7.85 04-003 Fly Ash Eastern Bituminous 0.685 9.35 8.54 04-035 Fly Ash Fort Union Lignite 0.159 12.73 12.74 04-036 

Fly Ash + Enhancing Agent + Activated Carbon

Enhancing Agent on Coal, ACI Pre-Primary PCD Fort Union Lignite 0.287 12.72 12.77 

04-043 Fly Ash Gulf Coast Lignite 0.689 11.65 11.28 05-001 Fly Ash Fort Union Lignite <0.01 12.67 12.51 05-003 

Fly Ash + Enhancing Agent + Activated Carbon

Enhancing Agent on Coal, ACI before SDA Fort Union Lignite 0.565 12.62 12.29 

05-018 Fly Ash Eastern Bituminous 0.123 7.49 8.49 

Page 1 of 1
APPENDIX T 

FIELD INVESTIGATIONS TASK SAMPLE SET 

AND FUNDAMENTAL CHARACTERIZATION 

DATA 
ID No. Field Task Sample Type Notes Hg (μg/g) 10–15-Min pH Overnight pH 24-Hr pH Moisture Co

04-055 1 Fly ash <0.01 9.36 9.13 15.0% 04-056 1 Wet FGD material + mill rejects 0.188 8.62 8.51 21.3% 04-057 1 Wet FGD material + mill rejects 0.207 8.68 8.53 19.3% 04-058 1

Background Soil from Natural 

Grasslands 0.050 8.57 8.40 12.6% 

04-059 1

Bottom ash/mill rejects + wet 

FGD material 0.044 8.77 9.29 7.02% 

04-060 1 Wet FGD material 0.299 8.55 8.27 23.3% 04-061 1

Bottom ash/mill rejects + wet 

FGD material <0.01 9.08 9.72 16.2% 

04-062 1

Bottom ash/mill rejects + wet 

FGD material <0.01 9.78 10.33 28.8% 

04-063 1

Stabilized wet FGD material (with 

fly ash) 0.080 8.94 9.14 15.0% 

04-064 1

Stabilized wet FGD material (with 

fly ash) 0.250 8.72 8.63 23.5% 

04-065 1

Stabilized wet FGD material (with 

fly ash) 0.011 10.33 10.81 10.1% 

06-014 2 soil-peat moss mix 0.067 7.42 7.48 38.5% 

Page 1 of 1
APPENDIX U 

ALTERNATE FIELD TASK DATA
Table U-3. CCB–Soil Experiment Organomercury Results Compared to Soil

ID No. Replicate Period

Calculated 

CCB–Soil 

Mixture Hg 

Total (μg/g)

No. 

Days in 

Testing 

Period

OrganoHg 

Release Rate in 

Testing Period 

Compared to 

Soil (pg/g/day)

% OrganoHg 

Released Over 

Testing Period (From 

Calculated Total Hg) 

Compared to Soil

Years to Release 

100% Calculated 

CCB–Soil Mixture 

Hg at Measured 

Rate Compared to 

Soil

Above or 

Below Soil 

Release 

over Testing 

Period

Experiment 

Duration, 

Days

Cumulative 

OrganoHg 

Release Rate in 

Testing Period 

Compared to 

Soil (pg/g/day)

Cu

Organ

Over T

(From C

Hg) Co

03-060 1 1 0.426 19 -0.0047 -0.000021% -249,006 Below

03-060 1 2 0.426 22 -0.0008 -0.000004% -1,437,004 Below03-060 1 3 0.426 49 -0.0190 -0.000219% -61,439 Below03-060 1 4 0.426 77 -0.0005 -0.000009% -2,263,313 Below 167 -0.0063 03-060 2 1 0.425 19 -0.0038 -0.000017% -306,627 Below03-060 2 2 0.425 22 -0.0007 -0.000004% -1,675,948 Below03-060 2 3 0.425 49 -0.0200 -0.000230% -58,307 Below03-060 2 4 0.425 77 -0.0008 -0.000015% -1,422,466 Below 167 -0.0066 04-003 1 1 0.190 19 -0.0038 -0.000038% -136,582 Below04-003 1 2 0.190 22 -0.0001 -0.000001% -4,499,912 Below04-003 1 3 0.190 49 -0.0095 -0.000243% -55,157 Below04-003 1 4 0.190 78 0.0393 0.00161% 13,273 Above 168 0.0151 

04-003 2 1 0.190 19 -0.0037 -0.000037% -142,075 Below

04-003 2 2 0.190 22 0.0003 0.000004% 1,665,484 Above

04-003 2 3 0.190 49 0.0006 0.000015% 923,520 Above04-003 2 4 0.190 79 0.0239 0.000990% 21,857 Above 169 0.0110 

04-029 1 1 0.106 15 0.0003 0.000005% 884,116 Above

04-029 1 2 0.106 25 -0.0002 -0.000006% -1,232,013 Below

04-029 1 3 0.106 50 -0.0159 -0.000753% -18,201 Below04-029 1 4 0.106 79 0.0029 0.000215% 100,622 Above 169 -0.0033 04-029 2 1 0.106 15 -0.0004 -0.000006% -720,231 Below04-029 2 2 0.106 26 0.0019 0.000047% 150,686 Above

04-029 2 3 0.106 49 -0.0160 -0.000744% -18,046 Below

04-029 2 4 0.106 79 0.0031 0.000233% 92,817 Above 169 -0.0030 04-054 1 1 3.60 19 -0.0039 -0.000002% -2,551,068 Below04-054 1 2 3.60 22 -0.0001 0.000000% -146,858,672 Below04-054 1 3 3.60 49 -0.0136 -0.000019% -723,001 Below04-054 1 4 3.60 81 0.0037 0.000008% 2,645,740 Above 171 -0.0026 04-054 2 1 3.60 19 -0.0043 -0.000002% -2,313,976 Below04-054 2 2 3.60 22 -0.0002 0.000000% -50,784,241 Below04-054 2 3 3.60 49 -0.0147 -0.000020% -671,982 Below04-054 2 4 3.60 81 0.0008 0.000002% 12,857,511 Above 171 -0.0044 05-009 1 1 0.060 19 -0.0033 -0.000105% -49,631 Below05-009 1 2 0.060 23 0.0002 0.000008% 811,862 Above

05-009 1 3 0.060 48 -0.0190 -0.00152% -8,632 Below

05-009 1 4 0.060 78 0.0093 0.00121% 17,649 Above 168 -0.0015 05-009 2 1 0.060 19 -0.0033 -0.000105% -49,790 Below05-009 2 2 0.060 23 0.0002 0.000006% 1,001,620 Above

05-009 2 3 0.060 48 0.0047 0.000376% 34,951 Above05-009 2 4 0.060 78 0.0254 0.00331% 6,456 Above 168 0.0127 

05-025 1 1 2.58 19 0.0034 0.000003% 2,060,761 Above

05-025 1 2 2.58 21 0.0057 0.000005% 1,239,898 Above05-025 1 3 2.58 50 -0.0092 -0.000018% -771,837 Below

05-025 1 4 2.58 82 0.0125 0.000040% 565,151 Above 172 0.0044 

05-025 2 1 2.58 19 -0.0038 -0.000003% -1,843,196 Below

Page 1 of 2
ID No. Replicate Period

Calculated 

CCB–Soil 

Mixture Hg 

Total (μg/g)

No. 

Days in 

Testing 

Period

OrganoHg 

Release Rate in 

Testing Period 

Compared to 

Soil (pg/g/day)

% OrganoHg 

Released Over 

Testing Period (From 

Calculated Total Hg) 

Compared to Soil

Years to Release 

100% Calculated 

CCB–Soil Mixture 

Hg at Measured 

Rate Compared to 

Soil

Above or 

Below Soil 

Release 

over Testing 

Period

Experiment 

Duration, 

Days

Cumulative 

OrganoHg 

Release Rate in 

Testing Period 

Compared to 

Soil (pg/g/day)

Cu

Organ

Over T

(From C

Hg) Co

05-025 2 2 2.58 21 0.0004 0.000000% 16,069,573 Above

05-025 2 3 2.58 50 -0.0053 -0.000010% -1,344,485 Below

05-025 2 4 2.58 82 0.0004 0.000001% 17,531,901 Above 172 -0.0016 05-038 1 1 0.074 15 -0.0022 -0.000044% -92,695 Below05-038 1 2 0.074 25 -0.0002 -0.000005% -1,350,142 Below05-038 1 3 0.074 49 -0.0170 -0.00113% -11,913 Below05-038 1 4 0.074 79 -0.0005 -0.000059% -369,850 Below 168 -0.0055 06-014 1 1 0.067 1506-014 1 2 0.067 2506-014 1 3 0.067 4906-014 1 4 0.067 78 167

Page 2 of 2